Science Fair Project Ideas for Evergreen Elementary School

Science fairs aren't just for older kids! If you're an elementary student, you can learn a lot and have a great time doing your own project. For grades K-3, a demonstration of scientific principles is usually okay, although many fairs require real experiments. For 4th graders, a complete experiment that answers a question using the scientific method (see below) is usually required.

Participating in a Science Fair Benefits Students

• If students are interested, they will learn and excel.
• A Science Fair has the potential to get students interested in science, engineering and mathematics.
• Science Fairs can make science relevant to a student
• Limited by student’s imagination
• Ideas can come from a student’s personal environment, current events and hobbies
• We all learn in different ways
• Research can appeal to one’s natural curiosity
• The work involved in creating a science fair project develops and reinforces successful work and life skills
• Teamwork, Time Management, Responsibility, Discipline, Ethics, Organizational Skills, interviewing, communication, working with mentors
• Participating in a Science Fair is a great for a student’s confidence.
• Science fairs can be a venue for students to network with others in their field of interest
• Students can win funds for college
• Participating in a Science Fair is a hands-on experience, a very important aspect of learning science.
• Science and engineering and mathematics are a human endeavor

The commercial site hometrainingtools.com has some science fair supplies for more project ideas and easy to use kits appropriate for grade school. It is an excellent starting point source of ideas for elementary school science experiments. (No affiliation, I just found the site incredibly useful)

Before you start the experimenting part of your project, do some research about your topic and then use questions like the ones below to develop your own hypothesis - what you think will happen in your experiment, based on what you know (or want to find out) about science. It's okay if your experiment doesn't turn out like you predicted - that's part of the scientific method too!

Life Science Ideas: Plants & Animals

• Have you noticed how the seeds in different kinds of fruit (like an apple and an orange) look very different from each other? Try growing seeds from different fruit or vegetables that you've eaten, soaking them in water for one night and then planting them in a cup of dirt. Which seeds do you expect to grow best? After doing the experiment, which seeds really grow best? (Which seed turns into the tallest plant after a month?) Why do you think that might be?

• Lots of factors affect plant growth. Try experimenting with soil type, light, temperature, water, and more. You can use a root viewer to experiment with root vegetables.

Flower Science Projects

Watch Seeds Sprout

What You Will Need:

• a clear plastic cup.
• potting soil
• bean seeds
• water
• sunny windowsill

What To Do:

1. Fill the cup about 3/4 full with potting soil.
2. Push a seed along the side of the cup into soil. Cover the hole with soil. You should be able to see the seed from the outside of the cup, but not the top. Repeat all around the cup, leaving a little room to grow in between each seed.
3. Water the soil. It should be moist, but the water should soak in and not stay on top of the soil.
4. Set your cup in a windowsill or another warm, sunny spot. Turn the cup every few days to make sure all of the seeds get sunlight.
5. Look at your seeds every day and water them whenever the soil looks dry.

What's Happening?

When you gave the seeds the right conditions, they started to grow within a few days! What conditions did you provide for your seeds? You gave them soil, water, sunlight, and warmth. A plant needs all of those conditions in order to grow.

You can probably see tiny roots growing from your seeds down into the soil. Plants use roots to get water and nutrients from the soil. You should also be able to see a small green stem sprouting up above the soil. This stem will continue to grow from the nutrients and water it gets from the roots. The plant will eventually grow leaves. Leaves use sunlight to make and store more food for the plant to use as it keeps growing. Soon your little plants will be too big for the plastic cup. Ask an adult to help you find a place outside or in a large pot where you can plant them and continue to watch them grow.

After awhile, the plants will grow little buds that will bloom into flowers. The flowers will eventually turn into a fruit - in this case, they will grow into bean pods! Inside of these fruits is where more seeds are formed for the next batch of plants to grow from. If the flowers of a plant don't grow into a fruit, the seeds are formed inside the flower instead.

Mini Flower Garden

This project has two parts - in the first part you'll plant flower seeds in an egg carton and watch them sprout into plants. In the second part, you will experiment to see what happens if your plants don't get enough water or sunlight. Ask an adult to help you do this project!

What You Will Need:

• an empty cardboard egg carton (not Styrofoam or plastic!)
• scissors
• plastic wrap
• potting soil
• flower seeds (look for seeds that grow quickly)
• water
• sunny windowsill or other warm place
• a marker
• 3 sheets of black construction paper
• masking tape (or any tape that isn't clear)
• kid friendly visual worksheet chart chart for printing

What To Do, Part 1:

1. Open the egg carton and carefully cut the top and bottom halves apart. Line the lid with a piece of plastic wrap to make a tray. Set the bottom half (the part with the 12 little sections) of the carton into the tray you just made.
2. Fill each section about 3/4 of the way full of potting soil.
3. Have an adult help you read the back of the package of your flower seeds to find out how deep to plant them. Poke three or four little holes in the soil in one section using your pinky finger. Make the holes as deep as the package says to plant the seeds. Put one seed into each hole, then cover the seeds with a little more soil.
4. Repeat step four in each section of your garden so that each one has 3-4 seeds planted.
5. Sprinkle some water into each section to water the seeds. Don't add too much - just make sure the soil looks a little bit wet.
6. Carefully move your whole garden to a warm place that gets a lot of sunlight, like a windowsill.
7. Look at the soil in each section every day. Do you see any signs that your seeds are growing? If the soil looks dry, add some water. If it still feels moist, check it again tomorrow.
8. Once all of the plants have grown at least 2 inches tall, you can begin Part 2 of the experiment.

What To Do, Part 2:

Start this part of the experiment in the morning so that you can check on your plants after a whole day of sunlight. Use the same worksheet chart to keep track of your garden during your experiments!

1. Draw a line down the middle of the carton (the short way) so that there are six sections on each side of the line. Draw a star on one side of the carton. The six sections between the star and the line are the ones you will experiment with. Let's call this the test half. The other half of the garden will be called the control half, because you will not change anything about how you take care of the plants in that half.
2. Draw a star on the worksheet in the same place as the one on your garden. This is a chart to help you keep track of the test half.
3. Choose three sections in the test half of your garden for a sunlight test. These plants will still get the same amount of water as the control plants, but they will not get any light!
4. Make a cone to cover the plants: roll up a sheet of black paper into a narrow cone shape and tape the edge. Put a piece of tape over the top to block more light. Make three cones and put them over the sections you chose to test. Make sure the cones completely cover the plants.
5. Mark the circles on your chart to show which sections will not get any light (cross out the sunlight and circle the water).
6. The other three sections of plants in the test half are for a water test. These plants will still get the same amount of sunlight as the control plants, but they will not get any water!
7. Mark the circles on your chart to show which sections you are not going to water.
8. Look at your chart and water all of the sections in the garden with an equal amount of water, except for the three from step 6 that do not get water.
9. Put your garden in a sunny spot and leave it there all day. After the sun sets, check on your plants. Carefully lift up the cones to check the sunless plants. If you see any changes, you can draw pictures on the worksheet. If nothing has changed, put the cones back on. In the morning, water them again, and leave them for another day. Continue to check and water them until you can see a difference between the plants. It might take several days, depending on how much sunlight they are getting and the type of flowers you are growing.
10. When you are finished with the experiment, make sure you take the cones off. The plants in the test half may need some extra-special care to get back to health!
11. When your plants outgrow the egg carton cups, ask an adult to help you cut the cups apart with scissors and plant each one in a pot or outside in a real garden, if you have one. Dig a hole just big enough to set the egg carton cup in. You can plant the whole cardboard cup in the soil right along with the plant; it will break down in the soil over time. Push dirt around the plant to hold it up and cover the hole. Make sure you continue to water your plants!

What's Happening?

Part 1: For the first few days, you probably didn't see much going on in your flower garden. After about a week, some little green stems should have begun to sprout up out of the soil in some of the cups. This is the first sign that your flower plants are growing, even though they had already been growing for some time below the soil, like you saw in the last experiment. Keep watering your young plants and you will be amazed at how quickly they will grow! Soon little leaves should start to appear on the stems.

Part 2: What did you notice about the plants that didn't get any sunlight? Their stems and leaves probably started to look a little more yellow than the other plants. They might have wilted some or not grown as tall as the control plants. Even though these plants were getting the same amount of water as the other plants, they weren't getting any sunlight! Water isn't enough to keep a plant healthy. Why not? Well, plants use sunlight to create food. When they don't get any sunlight, they can't create food! Plants need water and food to survive!

What did you notice about the plants that received the same amount of sunlight as the control plants, but no water? Did the plants start to wilt without water, or do they just not grow as much as the others? At first you might not have noticed any difference at all, but once the soil dried out, the plants' roots started to run out of water and the plants probably started to wilt and maybe even wither or shrivel up a little bit. Even though these plants were still getting plenty of sunlight, they still couldn't make food, because water is one of the things required for plants to be able to make food!

Skeletons and Bones Science Projects

What Makes Bones Strong? What would happen if we did not get enough calcium?

Even though bones are very light, they are also very strong. However, how strong they are depends on how much of the mineral calcium carbonate they contain. Do this experiment to find out how calcium carbonate affects bone strength. Make sure you get an adult to help you!

What You Will Need:

• Dried, clean chicken bone (a leg or wing bone)
• A glass
• White vinegar

What To Do:

1. Without breaking the bone, hold the bone and try to bend it - don't force it to bend; or it will break! Notice how stiff the bone is.
2. Place the chicken bone in the glass and fill it with vinegar.
3. Let the bone soak for 2-3 days, then pour out the vinegar.
4. Add fresh vinegar and let it soak for about 2 more days.
5. After the 4th or 5th day of soaking, take the bone out and dry it off. Now try bending the bone without breaking it. What do you notice? How does it feel different from before you soaked it in vinegar?

What's Happening?

Bones are made of calcium carbonate and a soft material called collagen. When the chicken bone was placed in the glass of vinegar, the acid in the vinegar dissolved the calcium carbonate so that only collagen was left. Calcium (the mineral in calcium carbonate) is needed to make our bones strong. When there isn't enough calcium, our bones become soft and are more likely to break. The soft collagen simply isn't strong enough to support our bodies on its own. But don't worry, the acid found in some food and drinks won't destroy your bones. Just make sure you eat plenty of foods that have calcium in them! A few foods that contain a lot of calcium are milk, cheese, soy products, beans, almonds, and orange juice.

What Makes Your Back Flexible?

What gives you the ability to bend, twist, run, or skip? Does having a lot of bones or just a few bones in your body make you more flexible? Try this experiment and find out! Make sure you have an adult help you.

What You Will Need:

• Drinking straw
• Pipe cleaner
• Scissors

What To Do:

1. Thread the pipe cleaner through the straw. Then gently try to bend the pipe cleaner where it is covered in the straw. Does the pipe cleaner bend much?
2. Take the pipe cleaner out of the straw and cut the straw into pieces that are about one inch long. Thread the pieces of the straw onto the pipe cleaner so that they are touching each other.
3. Now gently bend the pipe cleaner again. How easily does it bend?

What's Happening?

The pipe cleaner and straw are representing how joints allow our bodies to move. When the straw was in just one long piece, it was representing one long bone, such as our thigh bone or upper arm bone. These bones can't bend because there is no joint there to allow that to happen. Instead, these solid bones give our bodies stability. But when the straw was cut in pieces and then placed on the pipe cleaner, it was very easy to bend because of the "joints" created by the cuts in the straw. A joint is where two or more bones meet.

The small pieces of straw stacked on top of each other are very similar to how our bodies' backbone is structured. Your spine is made up of small bones stacked on top of each other with the spinal cord threaded through them. Like the pipe cleaner, you can bend your back forward and backward, side to side, and even rotate in a circle. The stacked bones are not very stable though, so your back has strong muscles to help keep your spine straight.

Your body has a lot of other joints too - bend your arms and legs, wiggle your fingers and toes, sit down, reach up high, and look from side to side. It is possible for you to move your body in all of these ways because of joints in your fingers, ankles, knees, hips, elbows, neck, and everywhere else that bones connect inside of your body!

Germs Science Projects

How Do Germs Spread?

What's the best way to wash our hands to keep us safe from germs? Use lotion and glitter to simulate germs. Experiment to find out if warm or cold water works better, which kinds of soap work best, and how much time you should spend washing.

Do you get told to wash your hands after playing outside or using the bathroom, even when there isn't any dirt on them? Try this experiment to see why you should wash your hands, even if they look clean!

What You Will Need:

• Hand lotion
• Glitter
• Sink or large bucket
• Paper towels
• Soap
• Water
• A helper

What To Do:

1. Put a drop of lotion on your hands and rub them together to spread the lotion out evenly.
2. With your hands over a sink or large bucket, have your helper put a pinch of glitter in the palm of one of your hands.
3. With your hands still over the sink, make a fist with the hand that has glitter on it, then spread your fingers out. What do you see?
4. Now press the palms of your hands together and pull them apart. What do you notice about your hands?
5. Touch your helper's hand. Now do you see anything on it?
6. Get a paper towel and use it to wipe your hands clean of all the glitter. Is it working?
7. After using the paper towel, try using soap and water to wash your hands. Did the glitter come off?

What's Happening?

After getting the glitter on your hands, you should have noticed it spreading very easily to anything you touched, even your helper's hand. When you tried to use a paper towel to remove the glitter, some of the glitter probably came off, but most of it stayed on your hands. But when you used soap and water to wash your hands, the glitter came off pretty easily. The glitter is acting the same way that the germs on your hands act - there are a lot of them, they spread around easily, and it can be tough to get them off. The difference is that germs are so small you can't see them without a microscope, so you have to know when you may have come into contact with germs and wash your hands often.

If you accidently touched your mouth, nose, or eyes while doing this experiment, you may have found glitter getting left behind near these areas. Germs travel the same way and can easily enter your body if you touch your face with dirty hands, which can make you sick. That's why it's important to wash your hands before you eat. It is also important to wash your hands after touching something that might have germs, such as when you use the bathroom or play outside. If you don't, the germs can easily spread to more places and to other people and cause sickness.

Growing Germs

Germs can be found just about everywhere, but some places have more germs than others. Try this experiment to see where germs are hidden. (Note: This experiment takes a week to complete.)

What You Will Need:

• An adult helper
• Gloves
• Potato
• Sharp knife
• 4 Ziplock bags
• Masking tape
• Marker

What To Do:

1. Have your adult helper wash his or her hands, put the gloves on, and then cut the potato in four equal pieces.
2. Take the first potato piece and put it in one of the bags. Seal the bag. Use the marker to write on the masking tape and label this bag as "control."
3. Pick a surface - such as a countertop, sink, or a floor - and while wearing the gloves, rub the second potato piece on it. Place the potato slice in a bag and label it with the surface it was rubbed on.
4. Take the third potato piece outside and lay it in a flower bed, a puddle, or something similar. Place the potato slice in a bag and label it with the outside area it was placed in.
5. Finally, touch the fourth potato piece all over with your bare hands. Place the potato slice in a bag and label it "touched with hands."
6. Take all four bags and place them in a dark area at room temperature, like a closet or cupboard. Leave them there for a week. After the week has passed, pull the bags out and look at the potato pieces. (Don't take the potatoes out of the bags.) What do you see on the pieces? Which potato has the most growth on it? Which potato has the least? Why do you think this is?
7. When you are done looking at the potatoes, have an adult pour a little bleach into each bag, seal the bags, and then throw them away.

What's Happening?

Do you see black, green, or white fuzzy stuff on your potato slices? These are germs, called mold or bacteria, growing on the pieces. The number of germs has grown so large that now you can see them without a microscope (like the piece of bread in the picture). The potato pieces that were handled by you, rubbed on a surface, and placed outside probably had the most growth on them. That's because the potatoes picked up germs from those places. The potato piece that did not touch anything probably has the least amount of growth on it, because it didn't touch anything that had germs. But that potato piece is important, because it lets you see how many germs already existed on the potato. The other potato pieces probably had just as many germs on them from the start, but once they touched other things, the potato pieces picked up more germs and the germs began to grow more than the germs on the first potato.

Ant Science Projects

Have you ever watched ants carrying bits of food? What food from your kitchen do you think an ant or other insect would like best? What "bait" will probably attract the greatest number of different insect species?

Observing an Ant

Do you know where to find ants? The sidewalk or driveway are good places to look. You might even find some inside your house! It's hard to see ants in the grass since they are so tiny, but you can usually find them living under rocks or logs. Just be careful, because there may be other insects living there, too. Now that you know where to look, go outside and find some ants! When you find one, use a magnifying glass to get a closer look. Follow it around and watch what it does for as long as you can. If you have a bug viewer, you can catch one or two ants to get an even better look at them.

Do you know the parts of an ant? Look at the ant you found and answer these questions:

How many legs does it have?

How many segments or sections does its body have?

Do you know what the sections are called?

How many feelers does it have? Feelers are called antennae.

Can you tell what the ant uses its feelers for?

What Temperature Do Ants Like Best?

Do you get tired of running around and playing outside more quickly when it is very hot out? What if it is very cold out? Do you think temperature affects how fast ants move, too? If you have an ant farm, do this experiment and find out! (Or, if you don't have an ant farm, you can put a few ants in a jar with small holes in the lid instead.)

Look at the ants in your ant farm and notice how fast or slow they are moving.

Put your ant farm in the refrigerator. Make sure it does not tip over!

After 10 minutes, take the ant farm out and look at the ants again. How fast are they moving now? Are they moving faster or slower than they were before you put them in the fridge?

Why do you think that happened to the ants? Ants are cold-blooded just like all other insects and some other animals, like reptiles. Humans, as well as other animals, are warm-blooded. What's the difference? Well, cold-blooded animals are not able to control the temperature of their own bodies, but the bodies of warm-blooded animals try to stay at a certain temperature even if they are in a place that is very cold or very hot.

This means that when an ant is in someplace cold, its body gets cold very quickly. It is harder for ants to move around when they are cold! They are more active and can move much faster when they are warm. Not all types of ants like the same temperature though. For example, ants that live in the deserts of Africa like hotter temperatures better than ants that live close to the mountains in Colorado!

Ant Food - Are Ants Picky Eaters?

Find an anthill or a place where you have seen a lot of ants around. (Make sure the place is not in the house!)

Pick out a few foods that have different flavors or tastes and put each one into a paper cup. Here are some ideas to try: sugar, pancake syrup, half of a strawberry, salt, lunchmeat, something sour (half of a lemon or some lemon juice), and something bitter (used coffee grounds).

Set each paper cup on its side near the anthill or ant spot that you found.

Watch the ants for a while to see which cups they go to. It might take them awhile to notice the cups! Which cups did the most ants go to? Did they check out what was in each cup? Did you see any ants leave a cup and come back with more ants?

After the experiment:
What kinds of food do you think ants like best? Different types of ants eat different things. Almost all ants like sweet nectar but some also eat other insects and some eat seeds and fruit from plants.

Important Science Terms

Antennae (say an-ten-ee) - Insects (including ants, of course!) and some other types of animals have a pair of stick-like feelers attached to their head. These are their antennae. They are the animal's senses. Using its antennae, the animal or insect can smell, feel, taste, and possibly even hear!

Cold-blooded - A cold-blooded animal usually has a body temperature that is almost the same as the temperature outside, inside, or wherever the animal is located.

Warm-blooded - of course, this is the opposite of cold-blooded and means that the animal has warm blood. Also, a warm-blooded animal's body is not the same as the temperature around it. It stays at almost the same temperature all the time. A human's normal body temperature is 98.6 ° F.

Teachers and parents, click here for more about ants.

Bird Science Projects

How does the membrane and shell of an egg help protect a baby chick?

The Case of the Disappearing Eggshell

An egg is covered by a hard shell to help protect the chick growing inside. When the chick is ready to hatch, it breaks the shell open. Try this experiment to find out what a shell is made of:

What You Will Need:

• An egg from the grocery store
• A drinking glass
• White vinegar

What To Do:

1. Set a raw egg in a glass of white vinegar so that it's completely covered in the liquid. Bubbles should start to form on the surface of the egg.
2. Let the egg sit in the vinegar for about 3 days and then take it out and rinse it in water, being careful not to pop it. Does it feel different from when you put it in the vinegar? Does it still have a white shell?

What's Happening?

The eggshell disappeared! But there might be some chalky white stuff left on the egg. This is because vinegar is a type of acid that "ate" away and dissolved the calcium carbonate that the shell is made out of. (Chalk is also made out of calcium carbonate!) When something dissolves, it breaks into very tiny pieces and mixes with a liquid. You can see it happening if you put a sugar cube into a cup of hot water and stir. The sugar cube disappears as the sugar dissolves into the water.

You might be wondering why the egg white and yolk inside the shell stayed in the shape of an egg even though the shell is gone. This is because the egg has another covering underneath the shell; called a membrane. It is very thin and you can see the yellow yolk through it. The vinegar can't dissolve the egg membrane, but some of it was able to get through the membrane, making the egg swell up.

The Shrinking Egg

In the last project, the egg membrane let liquid in, making the egg swell a little bit. Do this project to see if you can get the egg to shrink!

What You Will Need:

• The egg without its shell from the previous project
• A drinking glass
• Corn syrup

What To Do:

1. Carefully place the egg in a glass of corn syrup, so the egg is covered.
2. Let the egg sit in the corn syrup for about 3 days. Then take it out and see what happened!

What's Happening?

The egg shrank! This is because the egg membrane let a bunch of water pass out of the egg to try to balance how much water was inside the egg and how much water was outside it in the glass. The very tiny parts that make up corn syrup (called molecules) were still too big to pass through the membrane, so none of the corn syrup got inside the egg. The egg lost a lot of water, but didn't get anything to take the water's place, so it looks a little funny! Do you think it would fill up again if you put it in a glass of water? Try it out!

The fact that the egg membrane can let some things through is very important for a baby chick. Air passes through the membrane, just like water did in this experiment, and that allows the baby chick to breathe while it's inside the egg.

All About Feathers

When baby chicks hatch, they are covered with tiny, soft, fluffy feathers called down. Down helps keep them warm. (It can keep us warm too, which is why quilts and coats are often stuffed with down!) As they grow older, chicks grow bigger feathers called contour feathers. These are colored on the tips and downy at the base (the part closest to the body) to help keep them warm. They also grow long, strong flight feathers on their wings and tail. Look at a feather up close to learn more about it:

What You Will Need:

• A large feather (you can try to find one outside, or buy one from a craft store. Feathers you find outside can be very dirty, so make sure you wash your hands when you're done with this project!)
• magnifying glass
• Velcro
• Water

What To Do:

1. Feathers help protect birds from getting drenched in the rain. Instead of soaking through them, water just slides right off! Turn on the water faucet so it is just a tiny trickle. Hold a paper towel underneath the faucet and watch how the water soaks right through. Next, put the feather under the trickle. What happens? The water should just roll off, leaving the feather dry. (If it doesn't, try turning the feather over.) Birds keep their feathers waterproof by putting a layer of oil on them. They get the oil from a place near their tail called a preen gland.
2. Look at a piece of velcro. Do you see how one side has tiny hooks that catch on to the other side? Bird feathers work a little bit like this. Take your feather between two fingers and rub your fingers down from the tip. The long, thin "branches" of the feather (called barbs) will separate into sections. Use a magnifying glass to look at the barbs: they are covered with tiny little hairs called barbules. Now take your fingers and smooth the barbs back together. The barbules catch each other and stick, like velcro. Sometimes you will see a bird rubbing its feathers with its beak. This is called preening and the bird does it to smooth the barbs back together.
3. What's that running down the middle of your feather? That's the rachis (say RAY-kuhs), and it makes the feather strong. Look at the very end, which is called the quill - does it look a little bit like a drinking straw? That's because it's hollow, to keep the feather from getting too heavy. People used to dip the quill in ink to use as a pen!

Leaf Experiments

Test Green Tea Leaves to find out what other pigments are present in them.

Leaf cells have a special feature: pigment-containing chloroplasts in certain cells that enable them to produce energy and their own food through photosynthesis. What does that mean? Well, the chloroplasts within a cell contain different pigments, which are what gives a leaf its color. Green chlorophyll is the most common type of pigment, but there are also xanthophylls (yellow), cartenoids (yellow, orange), and anthocyanins (red). The chlorophylls usually hide the other pigments, except when autumn comes along and chlorophyll begins to break down. This is why leaves turn different colors in the fall.

So then, what is photosynthesis? Simply put, it's the capture of light energy to produce food. Light energy from the sun is transmitted through a leaf's cells to chloroplasts, where chlorophyll and other absorbing pigments serve as receptors to collect the energy. In the process of photosynthesis, carbon dioxide from the air is converted into energy-rich carbon compounds called carbohydrates. As this happens, oxygen is given off into the air, providing the oxygen that we breathe.

You can test the importance of light energy in plant growth by doing a simple experiment. using 2-3 small plants. (Bean plants are a good choice, as they sprout quickly.) You'll need one to be the control, with normal growing conditions, either outside in sunlight or inside by a bright window. See how light effects growth by covering the other test plants with a paper bag or small box during part of the day. Try covering one for four hours during the morning, and another for the whole day. Observe changes to the plants over the course of a week. Which grows the best? What is the result of light-deprivation?

To find out more about leaf pigments, do this next experiment. First, you'll need to extract pigments from leaves. Collect several green leaves from different trees, a few from each one. Maples and others that have dramatic color changes in the fall will work best, but you can use any deciduous leaves (from trees that lose their leaves in the winter). Tear each set of leaves into several pieces and place them in a glass beaker or small drinking glass, then add just enough rubbing alcohol to cover them. (You can cover the containers with foil or plastic wrap to keep the alcohol from evaporating into the air.) Put the containers in a dish of hot tap water for about 30 minutes, until the alcohol turns green as the pigments from the leaves are absorbed into it.

Next, test to find out what colors are really present in a leaf. You'll need coffee filters, filter paper chromatography paper for this part of the experiment. Cut a strip out of the middle of a coffee filter, about one inch wide, for each of the leaf sets that you want to test. Tape one end of the paper to a pencil or stick, and suspend it across the container, with the other end just touching the alcohol and pigment mixture. A bit of the mixture will travel slowly up the paper. After about 30-90 minutes you should be able to see the "green" color break up into several different colors as the different pigments begin to separate. You'll see different shades of green, and perhaps other colors as well. Which leaves had the most colorful pigments? Based on your experiment, which trees' leaves do you think will turn the brightest and least brightest colors this fall? Try the experiment again with evergreen leaves or needles to compare the results.

Taking a Closer Look at Plant Cells

Learn even more about plants by studying different sections of real leaves. You can make your own microscope slide of a leaf section and view it under high power with a compound microscope see cell detail. All you need is a fresh leaf specimen (use one without many holes or blemishes), a plain glass microscope slide, slide coverslip, sharp knife or razor blade, and water.

Before you begin, make sure the leaf is clean and dry. Lay it out flat on your working surface and slice about a 1'' section crosswise out of the center using the knife. The cells surrounding the central vein of the leaf are what you will want to look at; so make sure you slice across a section of the vein. Then, starting at one of the short ends of the strip (the edges that you did not cut), tightly roll the leaf section. Carefully make several very thin slices off one end of the roll with a razor blade or knife. This is a "cross section" of the leaf.

Make a wet mount on a plain slide with the inner part of the leaf section facing up (so the inner cells are visible). You can do this by adding a drop or two of water over the leaf section and then covering it with the coverslip. Look at the slide with your microscope's 10x objective to see the general structure, and higher power to see cell detail. Record your observations on a copy on this free microscope worksheet .

Chemistry Ideas: Crystals, pH, Slime, and Glue

Water Experiments

Design a science fair project comparing and contrasting how long it takes ice to melt at room temperature compared to a warm stovetop or the refrigerator. Try thawing frozen fruit at the same time. Does it longer or the same amount of time to warm up as the ice? What if you add salt to the ice?

Surface Tension Experiments

Surface tension is one of water's most important properties. It is the reason that water collects in drops, but it is also why water can travel up a plant stem, or get to your cells through the smallest blood vessels. You can experiment with surface tension using just a few household items.

What To Do:

1. Start with a cup of water and some paperclips. Do you think a paperclip will float in the water? Drop one in the cup to find out. Since the paperclip is denser than the water, it will sink to the bottom of the cup.

2. Now find out if you can use surface tension to float the paperclip. Instead of dropping the paperclip into the cup, gently lay it flat on the surface of the water. (This is tricky - ” it may help to place a piece of paper towel slightly bigger than the paperclip in the water. Then lay the paperclip on top of it. In a minute or so, the paper towel will sink, leaving the paperclip floating on top of the water.) Even though the paperclip is still denser than the water, the strong attraction between the water molecules on the surface surface forms a type of "skin" that supports the clip.

3. Now put a drop of dish soap in the water. This will bind with the water molecules, interfering with the surface tension. The paper clip will sink. You can try floating other things on top of the water also - pepper floats well until you add dish soap. Can you find any other light items that will float?

Surface tension creates the "skin" on top of the water, but it is also what causes water to stick together in drops. Observe how these drops stick together by experimenting with water and a penny. All you need is a cup of water, a penny, and a medicine dropper. First make a prediction: how many drops of water do you think you can fit on the top surface of the penny? Add one drop. After seeing how much room it takes, do you want to rethink your first prediction? Now continue carefully adding drops until the water spills off the penny. Try this three times, recording the number of drops each time, and then find the average number of drops that can fit. Surface tension is the reason you can fit so much water on the penny. The water molecules attract each other, pulling together so the water doesn't spill. Try this experiment with different-sized coins. Predict how many drops you can fit on a quarter compared with the penny.

For one final surface tension experiment, start with a full glass of water. Predict how many pennies you can add to the water without the glass overflowing. Gently add pennies one by one. Because of surface tension, the water will rise above the rim of the glass before it spills! Compare your original prediction with the number of pennies you were able to add.

Freezing Point

Have you ever wondered why rivers and lakes freeze in the winter, but oceans do not? In this experiment we will see that it is the presence of salt in the ocean that makes it less likely to freeze.

Materials:

• 1-gallon freezer bag
• 1-quart freezer bag
• crushed ice
• salt
• thermometer
• 
  

What To Do:

1. Fill the gallon freezer bag half full with crushed ice. Add one cup of salt and seal the bag. Put on some gloves and knead the ice and salt until the ice has completely melted.

2. Use the thermometer to record the temperature of the saltwater mixture. Even though the ice has melted, the temperature should be less than 32°F (0°C).

3. Now put about an ounce of water in the quart freezer bag. Seal the quart bag and then put it in the saltwater mixture in the larger bag. Seal the larger bag also and leave it until the water inside the quart bag freezes.

How did the water freeze when surrounded only by saltwater? The salt broke apart the bonds between the water molecules in the ice, causing it to melt, but the temperature remained below the freezing point for pure water. Salt (and other substances dissolved in water) will always lower the freezing point. This is why water in the ocean rarely freezes.

Solar Purifier

When water evaporates from the ocean, it leaves salt behind. If you had no fresh water to drink, you could distill (or purify) ocean water by taking advantage of evaporation. Here's how:

Materials

• Water
• Salt
• Large bowl
• Short glass or beaker.
• Plastic wrap
• Masking tape
• Rock (or other small weight)

Procedure

1. Add salt to two cups of water and stir until it dissolves, then pour it into a large bowl.

2. Place a short glass in the middle of the bowl. (This glass should be shorter than the rim of the bowl, but taller than the level of the saltwater.)

3. Now cover the bowl with plastic wrap, taping the edges, if necessary, to get a tight seal. Place a small rock or other weight on top of the plastic directly over the glass in the bowl. This helps you collect the distilled water in the glass.

4. Put the bowl outside in the sun. Leave it for several hours, or for the whole day. When you check it again, there will be water in the cup. Taste it to find out of it's salty or fresh! (You can also use electricity to test it for saltiness by making a saltwater circuit.)

What happened? The sun warmed the water in the bowl until it evaporated, becoming a gas. When the gas rose and hit the plastic it condensed there in droplets (just like water vapor condenses into clouds). The droplets rolled down the plastic toward the weight and eventually fell into the glass (like rain falling from the sky). The salt was left behind in the bowl, making the water in the glass pure enough to drink.

• Your kitchen offers lots of chemistry ideas. How does cola or another soft drink compare in acidity with other common drinks or food? You can test acidity using pH paper. You can also use indophenol to test which fruits have the most vitamin C.

• Water is sometimes called "the Universal Solvent'' because it dissolves other substances so well. How well does water dissolve salt or sugar compared to other liquids (like oil, corn syrup, or vinegar)?

Bubble Science Projects

Experiment with surface tension by making bubbles. Can you make them in different shapes? Can you poke scissors through them without popping them?

Surface Tension and Soap

Find out how bubbles work with this experiment. You won't actually blow any bubbles, but you will learn the science that makes a bubble!

What You Will Need:

• 2 short glasses of water
• A pie plate or tray
• Liquid dish soap

What To Do:

1. Put the first glass of water in the center of the pie plate.
2. Slowly pour some water from the second glass into the first glass until it is very full and the water forms a dome above the rim of the first glass. Set the glass with less water aside.
3. Carefully stick your finger straight down through the dome of the water in the full glass and watch what happens.
4. Now put a small drop of dish soap on the tip of your finger and do the exact same thing - stick the finger with soap on it straight down through the dome of water. This time what happens?

What's Happening?

Water is made up of lots of tiny molecules. The molecules are attracted to each other and stick together. The molecules on the very top of the water stick together very closely to make a force called surface tension. Surface tension is what caused the water to rise up above the rim of the glass in the experiment - the water molecules stuck together to make a dome instead of spilling over the side. Why didn't the dome break when you stuck your finger through it? Why didn't the water spill over the glass? Well, the surface tension was strong enough that it just went around your finger. The water molecules still stuck to each other and nothing spilled! What happened when you put your soapy finger into the water? The soap on your finger broke the water's surface tension and some of the water molecules didn't stick to each other any more and they were pushed out of the glass!

The force of surface tension also creates bubbles. In plain water, the surface tension is strong and the water might make some bubbles, but they will not last very long and they will be very small, because the other molecules in the water will pull on the bubbles and flatten them. Soap needs to be mixed with the water to make bubbles that can float through the air. When you add soap, the water becomes flexible, sort of like elastic, and it can hold the shape of a bubble when air is blown into it.

Super Bubble Solution

Make your own bubble-blowing solution out of soap and water, then see what happens when you add a special ingredient to the bubble solution!

What You Will Need:

• Liquid dish soap (Joy or Dawn brands work best. Try to find one that doesn't say "Ultra")
• Distilled water (tap water is okay, but distilled water makes the best bubbles)
• 2 clean containers with lids
• Glycerin or light corn syrup
• Measuring cup
• Mixing spoon
• A plastic pipet (cut off the closed end to make a bubble blower) or a drinking straw
• Tape and a marker

What To Do:

1. Measure 6 cups of water into one container, then pour 1 cup of dish soap into the water and slowly stir it until the soap is mixed in. Try not to let foam or bubbles form while you stir.
2. Once the soap and water are mixed, go outside to test it. Dip the cut end of your bubble blower into the solution and let the extra drip off. Blow through the narrow end to make bubbles. Do you get a lot of bubbles? How big are they? How long do they last before they pop?
3. Have an adult help you pour half of the bubble solution into the other container. Put a piece of tape on the outside of the new container. Use the marker to label it "Super Bubbles."
4. Measure 1 tablespoon of glycerin or 1/4 cup of corn syrup and add it to the "Super Bubbles" container. Stir the solution until it is mixed together.
5. Dip your blower or straw into the new bubble solution and blow. Are these bubbles different from the plain soap and water bubbles? Are they bigger or smaller? Do they last longer or pop faster? Can you blow a really big bubble?
6. To make even better bubbles, put the lid on the container and let your super bubble solution sit overnight. You can add glycerin or corn syrup to the other container to make those bubbles better, too. (Note: If you used "Ultra" dish soap, double the amount of glycerin or corn syrup.).

What's Happening?

The first bubble solution was just soap and water. As you learned from the Surface Tension experiment, soap helps bubbles form. You probably got some small bubbles that didn't last very long from the soap and water. Then you added glycerin or corn syrup to the soap and water and probably noticed that the bubbles you blew were stronger and better than before. Did they last longer? Were they bigger? The glycerin or corn syrup mixes with the soap to make it thicker. When the water that is trapped between the layers of soap in a bubble evaporates (or dries up), the bubble will pop! The thicker skin of the glycerin bubble keeps the water from evaporating as quickly. You can probably also blow a much bigger bubble with the second bubble solution that you made than with the plain soap and water one. Adding glycerin or corn syrup makes bubbles stronger and helps them last longer. It makes super bubbles!

Bubble Tricks

After you make the super bubble solution and let it set for at least one day, try doing some of these cool bubble tricks! Can you think of any of your own tricks to do with bubbles?

What You Will Need:

• Super bubble solution in a container with a lid (from the experiment above)
• Pipe cleaners or wire
• Drinking straws
• Bubble blower (from the experiment above)
• Pointy objects like scissors and a pencil

How To Do The Tricks:

Trick 1 - A Square Bubble?

You will need two pipe cleaners and your super bubble solution for this trick.

1. Bend a pipe cleaner into a square. Wrap the ends around the sides of the square to hold it together. Fold the other pipe cleaner in half and loop it around one side of the square. Twist the ends together to make a handle. Use it as a bubble blower.
2. Dip the bubble blower into the bubble solution and slowly blow a bubble through it until the bubble comes loose from the wand. What shape is the bubble?

What's Happening?

The bubble was round even though it came from a square! Bubbles are always round when they detach and float through the air because the skin of soap always tries to take up the least amount of space it can and still keep the same amount of air inside the bubble. The soap molecules always stretch into a round shape automatically! A round shape takes up less space than a square shape. Try the trick again, but make a wand in any shape you want - what about a star or a triangle? Do bubbles from those shapes become round too?

Trick 2 - Don't Pop the Bubble!

You will need the super bubble solution, the lid from the container, a straw, and some objects with pointed ends.

1. Set the lid on the table so that the part with the lip is facing up. Fill the lid with bubble solution.
2. Dip your straw into the bubble solution container so that it is wet half way up the straw. Touch the straw to the lid and blow a bubble on the lid. Slowly pull the straw all the way out of the bubble.
3. Now dip the pointed end of your scissors (or any pointy object) into the container of bubble solution. Make sure they are completely wet. Poke the scissors through the wall of your bubble. Watch what happens. Try it again with other pointed objects, just make sure anything you touch to the bubble is wet. Can you stick your finger through the bubble?

What's Happening?

You should have been able to push the scissors through the wall of the bubble without popping it! When something wet touches a bubble, it doesn't poke a hole in the wall of the bubble, it just slides through and the bubble forms right around it. The bubble solution on the scissors filled in the hole that would have been made. If you try poking dry scissors through your bubble, you will see it pop instantly! (If it popped when you put the wet scissors in, something was probably too dry. Try it again and make sure anything that touches the bubble is completely wet with bubble solution.) For another trick, get one hand completely wet in the bubble solution then use the other hand to hold your bubble blower and blow a big bubble in the palm of your wet hand.

Science Words

Molecule - a very tiny part of a substance that is too small to see with your eyes. A water molecule is smaller than one drop of water!

Surface tension - molecules in a liquid are attracted to each other and make the top of the liquid very tight. The surface tension is what causes water to form drops. It also makes a dome shape across the top of a container that is filled to the top.

Evaporate - when a liquid dries up and goes into the air. The liquid is then in the air, but it is a vapor or a gas now and you can't see it. When we say the air is humid, it means that a lot of water has evaporated into the air and now water vapor (gas) is floating around in the air. It makes the air moist and heavy, and it might make you feel sticky when you go outside.

Kitchen Science Projects

Your kitchen makes a great laboratory! Learn about chemistry and biology topics as you explore there. And if you're looking for a science fair project idea, your kitchen is a great place to start. Most of these projects take about a week before you see any results.

Dissolve an Eggshell

Make an egg shell disappear without touching it! Set a raw egg in a glass of white vinegar (acetic acid), so that it's completely covered in the liquid. Bubbles should start to form on the surface of the egg almost immediately. Let it sit for a week and then carefully take the egg out. What happened? The acid "ate" away and dissolved the calcium carbonate that the shell is made out of! There might be some chalky white residue left on the egg that you can gently scrape off. The inside of the egg is still intact, though, because vinegar doesn't break down the egg membrane. The egg also swells up, because some of the liquid seeps inside it. You should be able to see the yellow yolk through the membrane. How does the shell-less egg feel? Pick it up carefully to avoid popping it.

You can also try the experiment with a peeled boiled egg (boil it for 10 minutes). What do you expect to happen? The vinegar actually doesn't eat up the egg, but makes it feel somewhat rubbery. You can also try this with chicken bones. After a week in vinegar, the bones will be rubbery, because they lost calcium and other hardening minerals.

Make Sugar & Epsom Salt Crystals

Use sugar and water to grow edible crystals! The sugar and water should be mixed in a 2:1 ratio, such as 1-1/2 cups of sugar and 3/4 cups of water. This works best with a small saucepan on the stove, although you can use a microwave instead.

1. Heat the water to boiling and then add the sugar, stirring until no more can be dissolved. (The solution is saturated.)

2. Continue to heat the solution until it is clear. Pour the solution into a glass, but go slowly so you don't get any undissolved sugar from the bottom of the pan in the glass.

3. Next, dip a clean piece of cotton string into the solution so that the lower part of the string is coated. Take the string out and let it dry, then suspend it in the solution, part in and part out, for a week. (You might tie one end to a pencil and set the pencil over the mouth of the glass.)

Once a saturated solution starts to cool, the loose solute (sugar, in this case) molecules start to join with the solute molecules on the string, while the solvent (water) molecules get closer together, losing more solute. The solute crystal gradually develops around the group of solute molecules on the string.

Epsom salt crystals are even easier to grow:

(Note: Unlike sugar crystals, the Epsom crystals are not edible.)

1. Fill two 6-8 ounce cups with warm water and stir Epsom salt into each until no more salt will dissolve. Tie a washer or other small weight to each end of a 12" piece of cotton string.

2. Set each end of the string in one of the cups, with the middle of the string hanging down loosely into a "u" shape. Set a plate underneath to catch the drips as the water and salt solution moves along to the middle of the string.

After a few days, you should see tiny crystals forming along the string. The air causes any leftover water to evaporate, leaving a solid crystal. After a week you can take the string out of the water and examine the crystals more carefully. You can also try this activity with table salt.

There might be a white buildup on the crystals from the minerals in the water or mixed with the salt. Try rubbing it off so you can see the clear crystals. If you can, use distilled water to avoid some of this mineral buildup.

If you have a microscope or magnifying glass, compare the sugar and Epsom salt crystals to each other to see if they have a similar crystal structure. You can also compare the crystals to a few grains of sugar and of Epsom salt.

Homemade Ice Cream & Butter

After hundreds of years, the best ice creams are still made with fairly simple ingredients: milk, cream, sugar, and maybe eggs. You can make ice cream using simple ingredients!

Materials

• 1/2 cup milk
• 1/2 cup cream
• 1/4 cup sugar
• 1/2 teaspoon of vanilla or other flavoring
• Quart-size ziplock bag
• Gallon-size ziplock bag
• Ice
• Rock salt
• Thermometer

Procedure

1. Stir the milk, cream, sugar and flavoring together in a bowl, then pour the mixture into a quart-size freezer ziplock bag.

2. Stick this bag inside a gallon-size ziplock, half-filled with ice and rock salt - about 2 cups of ice and 1/2 cup of salt. Salt lowers the freezing point of water, which causes the ice to melt at a lower temperature. The lower freezing point provides the temperature difference needed to transfer heat between the freezing ice cream ingredients and the melting ice. Use a thermometer to measure the temperature in the outer bag. Next, begin shaking the bag so that the ingredients are whipped together.

3. What do you expect to happen to the cream mixture? After five minutes of shaking, let the bag sit for a few minutes. Now take the temperature inside the gallon bag again. Has it changed? What happens if you don't shake it? Rock salt doesn't lower the freezing point as much as table salt does (which results in smoother ice cream, because it freezes more gradually), but for this activity you can try table salt. Take the temperature

Ice cream is a colloid, an emulsion where two substances are just suspended within each other rather than being chemically bonded together. This is why many ice creams also have an emulsifier to prevent the fat molecules from separating from the rest of the ice cream (this makes the texture of the ice cream smoother). Ice cream also uses a stabilizer (like gelatin or guar gum) to help hold air into the ice cream, which gives it its light texture. To be officially called ice cream, the colloid has to be at least 10% milk fat and 6% non-fat milk solids (such as proteins).

Butter is made in a similar way. Pour some heavy cream into a small jar, screw the lid on tightly, and shake the jar briskly for 10-20 minutes. The butterfat molecules in the cream collide as you shake the jar, and they begin to stick together, forming butter and leaving the watery liquid of the cream separate. You'll notice a change in how the sloshing sounds and how heavy it feels. (Regular milk has a lower fat content than cream. Can you still make butter using whole milk? Skim milk has had so much fat removed that it can't be used for butter.)

Seashore Science Projects

Project 1: Observing the Seashore - Go on a Scavenger Hunt

The next time you visit the seashore, be a beach scavenger! You will see lots of different and very interesting plants and animals. Count them as you go to see how many different forms of life you can spot. A scavenger has to be very thorough and look in every place he can think of, so here is a guide to help you as you go.

Above the sand on the beach among the rocks, drifted logs, grass, and other plants, look for these:

• Birds - they like to hunt food on the beach and along the water, but they usually live someplace farther away from the water, such as in tall grass or on top of high rocks.
• Tracks - birds, crabs, and other animals may have left tracks behind while they were out looking for something tasty to eat. Also look for broken shells or other signs left behind from an animal's meal.
• People - you will probably see a lot of other people at the beach, which could make it hard to find animals! Look for a quiet place on the beach with the fewest people.

On the beach, walk around on the sand that stretches along the ocean and look for these:

• Driftwood - this is wood that has been soaked in the salty ocean water for a long time. The tides often carry it onto the beach where it might get stuck and stay for days or even years, depending on the size of it.
• Seaweed - move it around with a stick to see if anything got tangled up in it.
• Insects - get down close to the ground and look for bugs in the sand who are searching for food.
• Snails - you might find snails that are hiding inside their shells, or you might find empty snail shells.
• Crabs - you don't want to get too close to these guys, they can pinch!
• Jellyfish - be very careful; never touch a jellyfish or get too close to it even if it looks like it is dead - it can still sting you!
• Birds - what are they doing? They are probably looking for fresh food that has been washed up by the waves.
• Holes in the sand - what do you think those holes are from? Small creatures such as clams like to bury themselves in the sand to stay wet and cool while the tide is out. (When the tide is out there is less water on the beach and the sand starts to dry out in the hot sun!)
  
  Try This: If you find a hole in the sand, you can carefully dig under it and put the sand on a screen over a pan or bucket. Then gently shake the screen to sift the sand and see what you can find. If you find any live creatures, look at them quickly and then return them to the sand so that they do not dry out and die!
• If you are at a rocky beach: watch the rocks to see if you can spot any sea otters or seals. They might be hiding, hunting, or out sunning themselves.
• This is also a good time to find a quiet spot to sit down and watch for life around you! Keep track of everything you see and watch what the animals do.

Along the shore's edge, where the water and waves first touch the sand of the beach, look for these:

• Seaweed or algae.
• Plankton - very tiny plants and animals that float near the surface of the water.
• Small fish.
• Shells from ocean creatures - how many different kinds can you find?
• Look out across the ocean and watch for more life. Can you see dolphins or fish jumping out of the water? Do you see birds flying over the ocean?
  
  Important: Be careful when you are on the shore! If you wade in the ocean water, make sure you have an adult watching to warn you of any high waves that could hurt you.

When you get home from your seashore exploration, print out this coloring page and color the animals and other things that you saw.

Project 2: Dry Sand or Wet Sand?

Sometimes sand is perfect for making sandcastles and at other times it just falls apart. When is sand the best for making sandcastles? Do this experiment to find out!

What You Will Need:

• A plastic tub or container
• Dry sand (enough to fill your container 1/2 full)
• Water
• A seashell (or some other solid object)

What To Do:

1. Fill the plastic tub about 1/2 full with dry sand. Tilt the tub back and forth and watch how the sand moves.
2. Add water to the tub until the sand is wet enough to pack together. Now try tilting the tub back and forth. What happens?
3. Press a seashell or other object into the wet sand and then remove it. What do you see?
4. Now add more water until the sand is really soft and mushy. Tilt the tub again and see what happens to the wet sand.
5. Press a seashell into the sand again. What happened this time?

What's Happening?

When the tub was tilted back and forth with the dry sand in it, the grains of sand easily moved past each other. But when you added water, the water surrounded each grain of sand and the surface tension of the water caused the grains of sand to stick to each other making the sand more solid, kind of like clay. That is why the seashell left an impression in the sand. Sand that is damp like this works great for making sandcastles because it holds together so well.

When you added more water to the already damp sand, the sand became saturated. Saturated means that it has already soaked up as much water as it can hold. That made the the grains of sand separate from each other and they could no longer stick together. This time when you pressed your shell in, did the sand keep the shell's shape? Probably not. Sand that is too wet can't hold the shape of an object since the sand grains can't stick to each other. That means that sand that is too wet doesn't work well for sandcastles because the grains cannot stick to each other.

Project 3: Salt From the Sea

Have you ever accidentally gotten ocean water in your mouth? If you have, you know that ocean water is very salty! Water evaporates from the ocean every day, but what happens to the salt in seawater after the water has evaporated? Do this experiment to find out!

What You Will Need:

• Seawater (or salt and water to make your own)
• 2 or 3 jars
• Food coloring
• A piece of aluminum foil
• Eye dropper

What To Do:

1. If you don't have real seawater, you can make some saltwater by mixing 3-4 tablespoons of salt with 1 cup of water. Use hot water from the faucet so that the salt will dissolve easily.
2. Pour some of your seawater into each jar and add a few drops of a different food coloring to each jar.
3. Using the eye dropper, drop some seawater onto the foil. Be creative and make designs using your different colors of seawater solutions.
4. Allow the seawater to dry up. This may take several hours. To help speed up the process, put your foil and seawater in the sun.
5. After the water has evaporated, what do you see on the foil?

What's Happening?

After the water has evaporated, you should see tiny salt crystals where the seawater used to be. (The food coloring stuck to the salt crystals, making them easier to see.) When the water evaporated, the salt got left behind. The same thing happens to the saltwater in the oceans. However, fresh water is constantly being added back to the oceans through rivers and rainfall. If fresh water was not being added to the oceans, the oceans would slowly become saltier as the water evaporates.

Click here to learn more about the seashore.

Polymer & Slime Experiments

Polymers are very large molecules, formed by repeated patterns of chemical units strung together. Although "polymer" might bring to mind rubber or slime, did you know that there are polymers all around us, including inside our bodies? The protein DNA, which is the "blueprint" for cellular reproduction, is a naturally-occurring polymer. The protein casein, in cow's milk, is a polymer as well. Other natural polymers are cellulose and starch. Bone, horn, cotton, silk, rubber, paper, and leather all come from naturally-occurring polymers!

There are manmade polymers, as well. Fabrics such as rayon and polyester, polystyrene (used in styrofoam coffee cups), and PVC (used in pipes) are common examples of these artificially-occurring polymers.

You can use the following recipes to learn more about non-edible, naturally-occurring polymers. (Adult supervision recommended.)

Homemade Glue

Experiment with polymers by using milk proteins to make homemade glue. How does homemade glue compare with glue from the store? Can you develop a way to make homemade glue stronger?

Materials

• A tall, clear glass
• Non-fat or skim milk
• White vinegar
• Coffee filters or paper towels

Procedure

1. Did you know you can make glue using the polymers in milk protein? In a glass, put seven tablespoons of non-fat or skim milk—whole milk contains more fat, which can change the experiment results.

2. Add a tablespoon of white vinegar to the milk; you should see solids begin to form that are suspended in the liquid. The solids will have a grainy appearance. Allow them to settle toward the bottom of the glass, then drain the liquid off, using a coffee filter or paper towel.

3. Now, pat the solids with a paper towel to absorb any excess liquid. You can use the resulting slimy substance as glue--coat two pieces of paper with it, stick them together, and let it dry. How well does your homemade glue work compared to other glues?

When you added the vinegar to the milk, it caused the milk's protein, the polymer casein, to separate from the liquid part of the milk and clump together to form solids. Casein is used in adhesives, paints, and even plastics.

Polymer Slime

Does more or less of an ingredient make the slime more stretchy? What about slippery or gooey?

1. You can make a slimy substance using milk, vinegar, and baking soda. Form solids like you did in the glue project, using seven tablespoons of milk and one tablespoon of white vinegar. After the solids have formed within the liquid, use a coffee filter or paper towel to drain off the remaining milk.

2. Gently squeeze the filter or paper towel to wring as much liquid out as possible, and then use a paper towel to soak up any remaining liquid from the clump of solids. Next, mix baking soda with the solids; start with 1/4 teaspoon and then add more if necessary to pull the solids together. Make sure you mix the substance well! The end result should have the consistency and appearance of custard or thick vanilla pudding. Now you have a slime made from the polymers in milk protein!

For a different kind of slime, mix white glue (like Elmer's) with cornstarch and water. (White glue contains polyvinyl alcohol, a polymer.) Use four parts glue to one part cornstarch mixed with one part water: combine the water and cornstarch, and then add the glue gradually, stirring well. You'll need to let the mixture stand for several minutes before it turns to a solid putty-like slime.

How Does Acid Keep Apples Fresh?

Why do apple slices turn brown? Can you stop this from happening by using lemon juice? What else could you use?

Apples and pears are great for snacks or to have as a side dish for dinner. But keeping them looking white and delicious after they have been sliced can be tricky. Try this experiment to see how chemistry can keep your apples and pears fresh even after they have been sliced.

Materials:

• An apple or pear
• Sharp knife
• Lemon juice
• Clock
• Adult help

What To Do:

1. With adult help, cut the apple in half from top to bottom.
2. On one apple half, lightly coat the white part of the apple with lemon juice. Leave the other half uncoated. (The uncoated half is your "control" sample and let's you see what normally happens to a cut open apple.)
3. Observe the color of both apple halves, then place them white-part-up on a counter or tabletop.
4. Observe the apples again after 30 minutes. Notice any color changes and/or differences in appearance.
5. Look at the apples again periodically throughout the day. What do you find?

What's Happening?

When an apple is cut open, an enzyme called polyphenol oxidase is released from the cells of the apple and reacts with the oxygen in the air. This reaction causes the fruit to turn brown, similar to rust forming on metal. Almost all plants contain polyphenol oxidase, and it is believed plants use this enzyme as part of a defense mechanism. When a plant is damaged, the browning of the affected area is thought to discourage animals and insects from eating the plant any further. It also might help the plant heal because the browning creates an antibacterial effect, preventing germs from destroying the plant even more.

Lemon juice helps keep the apple from browning, because it is full of ascorbic acid (Vitamin C) and it has a low (acidic) pH level. Ascorbic acid works because oxygen will react with it before it will react with the polyphenol oxidase. However, once the ascorbic acid gets used up, the oxygen will start reacting with the enzyme and browning will occur. Lemon juice's low pH level also helps prevent browning. Polyphenol oxidase works best when the pH level is between 5.0 and 7.0. However, below a pH level of 3.0, the enzyme becomes inactivated. The pH of lemon juice is in the 2.0 range, making it very effective against browning.

Besides lemon juice, lime juice and cranberry juice also have a pH below 3.0. Concord grape juice and grapefruit juice also have a low pH (not quite as low as the others), but will help delay the browning process. You may want to try several of these juices and find a tasty to way to serve sliced apples and pears in the process!

Chemistry Projects

How does yeast make bread rise? What conditions make yeast react faster or slower?

Up, Up, and Away!

Well, your balloon might not quite fly away in this experiment, but you can make it inflate by creating a reaction in a bottle.

What You Will Need:

• 1 packet (or 2 teaspoons) of active dry yeast
• 1 tablespoon of sugar
• 1 cup of warm water
• A clean, empty plastic bottle (the kind soda or water comes in)
• A sheet of paper
• A balloon
• Notebook
• Pencil

What To Do:

1. Stretch the balloon out by blowing it up and releasing the air three times.
2. Pour the warm water into the bottle. Make a funnel by rolling a piece of paper into a cone shape, then put the pointed end into the mouth of the bottle. Pour the sugar into the bottle through your funnel. Put the cap on and shake the bottle until most of the sugar has dissolved. Take the cap off.
3. Put your funnel in the mouth of the bottle and pour the yeast in so that it floats on top of the sugar water.
4. Quickly attach the balloon to the mouth of the bottle.
5. Set the bottle in a place where it won't be disturbed and write in your notebook what time it is.
6. Go back and check the bottle after two minutes and write down changes you see to the liquid in the bottle or to the balloon.
7. Check it again in five minutes and write down any changes. If it doesn't look like much is happening, leave it for about 15 minutes and then look at it again.
8. Continue to check on the bottle and balloon about every 15 minutes. The reaction may continue for up to several hours. Watch closely and write down any changes you notice!

What's Happening?

The warm water made the yeast "wake up" and it immediately started to have a chemical reaction with the sugar. Two substances, yeast and sugar, reacted to each other and together they made a new substance - a gas called carbon dioxide. Carbon dioxide is the same gas that makes soda pop fizzy, and one of the many gases in the air we breathe in and out. The carbon dioxide from the reaction filled up all the space in the plastic bottle and kept rising to fill up the balloon. At first, the yeast should have have looked puffy or bubbly on the surface of the water as it was beginning to react with the warmth of the water. Then, you probably noticed that the balloon was standing straight up instead of being flopped over the mouth of the bottle! That was the first sign that the yeast was reacting with the sugar and that carbon dioxide gas was being made. Soon after that, the balloon should have started to inflate. Since the balloon was made of stretchy rubber (and you helped stretch it out), it kept expanding to hold the carbon dioxide, the same as it would if you were to blow it up with your mouth. When you breathe out (or exhale), your lungs push carbon dioxide out, along with a few other gases, which is how you are able to blow up a balloon.

Now that you know how it works, you might want to try the experiment with other types of sugar mixtures. What do you think would happen if you used your favorite soda or juice instead of the sugar water?

So, if yeast and sugar react this way in a bottle, what happens when you bake with them? Well, the same thing happens, it just looks a little different. Bread and many other baked goods are made from yeast. The yeast reacts with the sugar in the dough and releases carbon dioxide, which creates tiny air bubbles that pop and leave air pockets as the dough bakes into bread. You can get a closer look at the air pockets left behind in a slice of bread.

Slime Time

What You Will Need:

• White glue
• Water
• Food coloring
• Borax powder
• Glass or ceramic bowl
• Small mixing bowl or cup
• Measuring cup
• Measuring spoon
• Mixing spoon or popsicle stick
• A square of chocolate

What To Do:

1. Measure 1 cup of water into the small bowl or cup and add the Borax powder. Stir it well and set it aside. You just made a solution of Borax.
2. Rinse your stirring spoon to get all of the Borax solution off of it.
3. In the larger bowl, measure 1/2 a cup of water and 1/2 a cup of white glue. Stir it well until it is all mixed together.
4. If you want colored slime, add 2-3 drops of food coloring to the glue mixture now.
5. Pour the Borax solution that you made in step one into the glue mixture and start stirring. You should see a big clump form in the colored glue right away, just keep stirring though until the clump has picked up as much of the liquid around it as it can.
6. Now comes the fun part - set your spoon aside and pick up the slime with your hands. Keep it over the bowl and knead it like dough, working it between your fingers. As you play with it, the slime will dry off on your hands and will become less slimy and more like putty.
7. Keep your slime in a plastic zip-lock bag in the fridge when you are not playing with it.

What's Happening?

The slime you just made is called a polymer (say: PAUL-UH-MER). The word polymer means "many parts." White glue is one type of polymer. When you mixed water with the white glue, the glue formed long chains of thousands of little molecules that you couldn't see until you added the Borax solution. The Borax had a reaction with the glue - it linked all those chains together, which made the whole mixture thicker and turned it into a blob of slime, a different type of polymer!

There are lots different types of polymers, including plastic, rubber, Jell-O, glue, camera film, materials such as nylon, and even natural fibers from wood and cotton. This polymer has properties of a solid and a liquid at once. Compare your polymer to a solid object - a piece of chocolate. Break the chocolate in half. Try quickly breaking the wad of slime in half. Did you get a clean break similar to the way the chocolate broke? To see how it is also like a liquid, try slowly stretching the blob out between your hands. You can't do that with a solid piece of chocolate! The polymer is showing its liquid properties when you stretch it slowly. Now set the slime back into the bowl you made it in and watch what happens. It should flatten out to fill the bottom of the bowl, similar to a liquid like pancake batter would do.

Science Words

Chemical reaction - when two or more substances come into contact and form a new substance.

Carbon Dioxide - a gas that is in the air on earth, but in very small amounts. Plants need it in order to live; they use it to covert sunlight into food. Humans breathe out carbon dioxide when we exhale. In chemistry, it is abbreviated CO₂, which means that is has one carbon atom and two oxygen atoms.

Polymer - the word "poly" means many, so a polymer is a long chain of molecules that gives a substance the ability to stretch and be very flexible.

Earth Science Ideas: Weather and Dirt

Weather Experiments

The sun causes water to evaporate into the air, where it forms clouds and comes back down as rain or snow. Can wind speed, humidity, or temperature have an effect on the rate of evaporation? (Do one of these weather experiments to find out more.)

The science of weather affects all of us every day! Convection, high-pressure and low-pressure systems, evaporation--these things help determine if our game will be rained out or if we will have a sunny day for sledding. Learn more about the way weather works by doing these hands-on experiments.

Experiment 1: Convection Current

Have you ever heard that hot air rises? That's true! As air heats up, its molecules expand and spread out, making the air less dense than it was before. It floats up through the denser cooler air. As the warm air rises it starts to cool off and its molecules move closer together, causing it to sink again. This circulation is called convection, and the rising and falling of the air are called currents. Convection currents are part of what causes different kinds of weather. (You'll find out how in the next experiment.)

We can't see convection in the air; do you think water might act the same way? Do this experiment to find out!
You should have an adult help you with the hot water and the knife.

Materials

• Large glass jar or beaker
• Small cup or beaker (it needs to fit inside the jar)
• Food coloring
• Knife
• Plastic wrap
• Rubber band
• Water

Procedure:

1. Fill the small cup or beaker with very hot (almost boiling) water and add several drops of food coloring. Stretch the plastic wrap smoothly over the cup and seal it with the rubber band. (The plastic wrap will puff up--this is because the hot air above the water is expanding!)
2. Fill the jar almost full with cold water from the tap.
3. Use a pair of tongs to set the cup of hot water in the bottom of the jar.
4. Slice open the plastic wrap with the knife and watch what happens! (One long gash should do it.)

What happened? The hot water was less dense than the cold water surrounding it, so it rose to the top in a convection current. What happens as the colored water gets to the top? Does it stay there? Why or why not?

Experiment 2: Sea Breeze

Air seems like the lightest thing in the world, but it actually pushes down on you and the ground with a great deal of force. This force is called air pressure. Air pressure doesn't always stay the same; meteorologists measure its changes with a barometer. In the last experiment we saw that when air heats up it begins to rise. When it rises, it doesn't push on the ground with as much pressure. An area full of light, warm air is called a low-pressure zone. Areas with cool, denser air are called high-pressure zones. What happens when a low-pressure zone and a high-pressure zone are right next to each other? Do this experiment to find out! Have an adult help you with the oven and matches.

Materials

• Two metal pans
• Ice
• Sand
• Candle
• Cardboard box (if necessary)

Procedure:

1. Set up the experiment in an area where it will be protected from drafts. If you need to, you can make a three-sided screen by cutting off one side of a cardboard box.
2. Pour some sand into one of the pans and put it in the oven to heat it up. (300 degrees for 5-8 minutes.)
3. While the sand is heating up, light a candle and then blow it out. Which direction does the smoke flow? If you have protected your area from drafts, it should flow straight up just like your convection current.
4. Fill the second pan full of ice. Put the pan of hot sand and the pan of ice side by side. (Set the hot pan on a pot holder!)
5. Light the candle again and blow it out, then hold it in between the two pans, right above the edge of the ice pan. Which direction does the smoke flow?

What happened? When you lit the candle the first time you did it in an area where the air pressure was constant, so the smoke flowed straight up. When you set the pans side by side, the ice cooled the air around it, creating a mini high-pressure zone, and the sand warmed the air around it to create a mini low-pressure zone. Air always flows from a high-pressure zone to a low-pressure zone to even up the pressure - this is what causes wind. You made a tiny breeze between the pan of ice and the pan of sand, and the smoke floated sideways in the breeze. The same thing happens between cold ocean water and hot beach sand, which is why there is almost always a breeze at the beach!

Air pressure changes cause wind, but they are responsible for other types of weather too. A low-pressure zone usually causes clouds and rain, because as the hot air rises it carries with it evaporated moisture that can condense into clouds. A high-pressure zone usually results in clear skies and sunny days because sinking currents prevent moisture from rising up and forming clouds.

Try tracking the air pressure for a few days in your area and see how it relates to the weather. You can use a barometer, or check the National Weather Service website.

Experiment 3: Evaporation Station

Low-pressure zones create clouds because the rising hot air carries moisture with it. The moisture is in the form of a gas called water vapor. When the water vapor cools, it forms water droplets that join together to form clouds. How does the water vapor get into the air in the first place? Most of it comes from evaporation. Evaporation happens when water molecules warm up - they gain enough energy to change from a liquid into a gas, and then they rise up into the air to be carried on rising convection currents.. You have seen this happen in your kitchen when steam rises from boiling water.

Are there factors that can change how fast water evaporates? You can find out by setting up an experiment to test the effect of wind, temperature and surface area on the rate of evaporation. The following procedure will give you the basics, but feel free to come up with your own methods of testing and measuring the results. This kind of experiment would make a great science fair project. (Be patient: some of these tests can take more than one day!)

Materials

• two kitchen sponges (they should be the same size)
• electric fan
• lamp
• small glass or beaker
• pie pan or shallow dish

Question & Hypothesis: How do factors such as wind, temperature, and surface area affect the rate of evaporation? Will wind or heat cause water to evaporate faster? Will a greater surface area speed up or slow down evaporation? Write down your predictions.

Procedure:

1. Test the effect of temperature using an incandescent lamp to provide heat. Place two kitchen sponges on plates and pour 1/8 cup (C) water over each of them. (Depending on the size of the sponge, you may need to use a bit more water. Use enough to get the sponge wet all the way through.) Place one of the sponges directly under a lamp and the other at room temperature out of direct sunlight. Observe the sponges at regular intervals, and reduce the time between observation as they get nearer to drying. Record how long it took for each sponge to dry completely. Which sponge dried faster?
2. Test the effect of wind using an electric fan. Wet the sponges as you did in step 1. Set one sponge 12 inches away from an electric fan and turn the fan on. Set the other sponge some place out of the draft. Observe the sponges at regular intervals. Record how long it took for each sponge to dry completely. Which one dried faster? Did the sponge in the fan dry faster than the one under the lamp in step 1?
3. Finally, test the effect of more or less surface area. Pour 1/8 C water into a small glass. Find the surface area of the water in the cup using the equation pi=r ² (pi = 3.14, r = radius. Find this by measuring the diameter of the cup and dividing this by two). Pour 1/8 C of water into a pie pan or wide shallow dish. Measure the surface area of the water in this container. Set the cup and the pan on the counter and check them a few times a day. Which water evaporates faster - the water with the small surface area or the large surface area?

Conclusions: Were your predictions correct? Which speeds up evaporation more, wind or heat? Based on your results, do you think the temperature or speed of wind would affect the evaporation rate? Can you think of other factors to test or a more precise way to test these factors again?

Clouds, Precipitation, & Weather Forecasting

Can you learn to predict the weather from the clouds? Try using this Cloud Chart to make your own forecast every day for a few weeks. How accurate was the cloud-forecast method?

There are two main ways that a cloud is formed. Rising air currents form the first type, cumulus clouds, giving a heaped-up appearance. The second type, stratus, forms when a layer of air is cooled below its saturation (dew) point, which makes the cloud look like a blanket of fog.

To understand the daily weather, you should know what some of the basic clouds types are and what kind of weather they usually bring. Note that Cirro/Cirrus are high-altitude clouds, while alto are mid-range clouds.

Stratus: low-altitude, densely foggy clouds that can result in a light drizzle of rain or an overcast sky.

Nimbostratus: rain and snow clouds. These are low-lying clouds that are distinguished by their darker color; they also often have visible sheets of rain that extend from them. "Nimbus" means rain cloud. (Cumulonimbus clouds are thunderclouds.)

Stratocumulus: sheets of gray, puffy clouds that usually foretell bad weather.

Cirrus: high-altitude ice clouds (formed by ice crystals instead of water droplets) that appear as wisps. These often mean good weather for the immediate future.

Cirrocumulus: high-altitude ice clouds. They look similar to lower altocumulus clouds: although they are in denser sheets and often have a lighter color, they have the same fish-scale or ripple look as altocumulus. They usually foretell precipitation and thunderstorms.

Barometric pressure is another way to forecast approaching weather. A low barometric pressure or falling barometric pressure shows a change in atmosphere that usually means a storm is coming.

A Cloud Chart is an excellent tool to learn to forecast the weather from observing the clouds.

Make a Thermometer

How does a thermometer work? What kind of liquid works best to show changes in temperature?

A thermometer shows the temperature when liquid inside it moves up or down on a scale. Find out how it works when you make your own in this project.

Materials

• Plastic water bottle
• Modeling clay
• clear plastic straw
• Food coloring

What to do:

1. Put a few drops of food coloring into the water bottle and fill it to the top with lukewarm water.
2. Insert the straw a couple inches into the bottle and mold the clay around it to seal the bottle and hold it in place. When you have a tight seal, water should go up into the straw.
3. Use a marker to mark the level of the water in the straw.
4. Set the bottle in a bowl of hot water. Watch the water level for awhile and then mark the level again.
5. Set the bottle in a bowl of ice and watch what happens, then mark the level.

What's happening?

As water heats up, it expands and becomes less dense, rising to the surface. When it cools down, it contracts, becoming more dense and sinking down. This cycle is called convection. (Water is unique, however - when it gets cold enough to freeze, the molecules line up in an open crystalline structure that is actually less dense than the liquid form. This is why ice floats.) When the water in your bottle thermometer heated up, it expanded. But since the bottle was sealed, it had nowhere to go but up through the straw.

Real thermometers don't use water inside because it doesn't respond to temperature change very quickly. Try filling your bottle with 50% rubbing alcohol and 50% water. Does the liquid move up and down the straw faster? Why do you think this is?

With your homemade thermometer you aren't actually measuring temperature, just seeing temperature changes. If you have a real thermometer, you can use it to make a scale on your homemade thermometer: let your bottle get to room temperature and then mark the straw with what the actual room temperature is. Then set the bottle in the sun and do the same. Mark several different temperature levels and then watch your thermometer for a day and see how accurate it is.

Physical Science Ideas: Force and Energy

• Can you use a magnet to find traces of iron in food, dollar bills, and other household materials? Are some magnets stronger than others?

• What type of flooring creates the most or the least friction? Try carpet, wood, tile, linoleum, etc. Younger kids might test this by rolling a ball or toy truck over different surfaces. (Or use a spring scale to measure the force of friction.) Use this to decide what kind of flooring is safest (least slippery) for someone wearing socks.
• Why does a balloon stick to the wall after you rub it against your hair? Experiment with static electricity to find out how positive and negative charges in household items interact. What causes static electricity to increase? What are some ways to decrease static electricity, and which ways work best?

Energy Science Projects

Super-charged Balloon

Make a balloon stick to the ceiling and make your hair stick up on its ends as you learn about electrical charges.

What You Will Need:

• Large balloon
• Wool scarf or sweater

What To Do:

1. Blow up the balloon and tie the end, so no air can escape. Rub the balloon several times with the wool.
2. Bring the balloon close to your bare arm to watch the small hairs stand on end. You can also bring the balloon close to a friend's head and watch his or her hair stick out in all directions!
3. Bring the balloon towards your arm once more, this time letting it touch your skin. After it has touched your arm, will the balloon still raise your hair?
4. Rub the balloon with the wool again, then hold it next to a wall, moving it gently back and forth for a few seconds before letting go. With an adult's help, you can also try sticking the balloon to the ceiling.

What's Happening?

Have you ever gone down a slide at the playground, and felt your hair sticking up? The slide and your hair rub against each other and create static electricity, which can stick to any surface, unlike other types of electricity that only flow through wires. When you rub the balloon and wool object together, it gives the balloon an electric charge, meaning it is full of static electricity. This charge makes the balloon move towards the wall and stick there even after you move your hand. It also pulls the hair on your arm towards the balloon, even though your arm is not touching it. When the balloon does touch your arm, it loses its electric charge. The static electricity is transferred to your arm and then to the floor, where it spreads out until it has disappeared. Now if you move the balloon up to your hair, it won't stand up, since there is no longer any static electricity in the balloon. Rubbing the balloon again with the wool will create more static electricity and you can do it all over again.

Bend in the Stream

Bend a stream of water using a comb to see how static electricity can pull or push things!

What You Will Need:

• Kitchen or bathroom sink
• Hard rubber or plastic comb
• Wool scarf or sweater

What To Do:

1. Turn the faucet on so a small, steady stream is flowing. The stream should be no thicker than your pinky finger.
2. Rub the comb over the wool sweater or through clean, dry hair several times.
3. Hold the teeth of the comb close to the stream of water, but don't put the comb into the water.

What's Happening?

Did you see the stream of water bend towards the comb? The water was pulled towards the comb through static electricity. Rubbing the comb and sweater together created static electricity, which gave the comb an electrical charge. The electrical charge is what drew the water towards the comb. Water is neutral, meaning it cannot have an electrical charge, but it can be pushed away (repelled by) or pulled towards (attracted to) something with an electric force, like the comb that was full of static electricity.

Solar Hot Air Balloon

Use a trash bag to make a hot air balloon that gets its power from the sun! You will need to do this experiment on a warm, sunny day without wind.

What You Will Need:

• 1 black trash bag
• Twist tie
• String or yarn (about 8 feet long)
• Hairdryer (optional)

What To Do:

1. Take the twist tie, string, and trash bag outside to a cool, shady spot. Open up the trash bag and swing it around, filling it with cool air.
2. When the trash bag is full of air, close it up tightly using a twist tie.
3. Tie the piece of yarn or string around the bag near the twist tie, then take it out into the sun. Tie the other end of the string to a picnic table or chair in a sunny spot, away from trees. Watch to see if anything happens in the next few minutes. Come back later (it may take an hour or more) to see the results of your experiment. If you don't have time to wait, use the hairdryer to warm the air inside the trash bag, then quickly bring it outside and hold onto the string. Watch what happens.

What's Happening?

You should have eventually seen the trash bag slowly start to float up in the air. The sun not only gives light, it also gives heat. The color black absorbs a lot of heat, so the air inside of the black trash bag was warmer than the air outside it. As air heats up, it expands (spreads out), becoming lighter. Since warm air is lighter, it always rises above cool air. The black trash bag started to rise up as the air inside it got warmer. If you used a hairdryer to heat the air inside the bag, the same thing happened, you just used electrical power to heat the air instead of solar (sun) power! The fact that hot air rises is part of the reason why the lower level (or the basement) of a house feels cooler than the upstairs levels.

• The sun gives off energy that can be used like a battery to power things. Connect a motor to a solar cell and figure out what conditions it runs best under. Do different types of artificial light (such as fluorescent and incandescent) power a solar cell better than others? What happens on a cloudy day?

• Can salt conduct electricity? What about sugar? Do a project to test the conductivity of different materials using a battery and a light bulb or a buzzer.

Saltwater Circuit

Did you know that you can use salt water to make a light bulb shine? It sounds crazy, but it's true! This is because salt water is a good conductor of electricity.

Salt molecules are made of sodium ions and chlorine ions. (An ion is an atom that has an electrical charge because it has either gained or lost an electron.) When you put salt in water, the water molecules pull the sodium and chlorine ions apart so they are floating freely. These ions are what carry electricity through water. Watch it work in this project! (Adult supervision recommended.)

Materials

Cup or beaker	Masking tape
Water	• Insulated copper wire
Salt	9 volt battery
Aluminum foil	3.7-volt light bulb in a cocket or buzzer
Tongue depressors (or popsicle sticks)

Procedure

1. Wrap two tongue depressors in aluminum foil. These will be your electrodes.

2. Cut three 6-inch pieces of insulated copper wire and strip a half-inch of insulation off each end.

3. Connect one end of a wire to the positive terminal of the battery - hold it in place with masking tape. (If you are using a 9v battery cap, connect it to the red wire.) Connect the other end of the wire to the light bulb socket. (Just wrap the wire around the bottom of the bulb, if you don't have a socket. You may have to secure it with tape.)

4. Take the second piece of wire and connect the light bulb socket with one of the electrodes. Use masking tape to stick the bare end of the wire on the aluminum foil near the top the electrode.

5. Use the third piece of wire to connect the negative terminal of the battery with the other electrode.

6. Test out your circuit by touching the two electrodes together. This should complete the circuit and allow electricity to flow from one terminal of the battery to the other, lighting up the light bulb in the process. If the bulb doesn't light up, check your wire connections to make sure they are all secure and then try again.

Testing the circuit in water

1. Pour 1 cup water into a cup or beaker. (If you have distilled water, that will work best.)

2. Put the two electrodes in the cup, but don't let them touch each other. What happens to the light bulb?

3. Now stir in a teaspoon of salt until it dissolves. Put the electrodes in the salt water without touching them together. Watch the light bulb.

The light bulb lit up because the sodium and chorine ions conducted the electricity from one electrode to the other. This completed the circuit, causing the light bulb to shine. Try adding more salt and see if the light bulb shines brighter. Use a buzzer instead of a light bulb and see if more or less salt in the water makes the buzzer ring louder or softer.

• Use a spectroscope to compare the spectra (which looks like a rainbow) of different types of light. Do different light sources contain different colors? How does daylight compare with a fluorescent light bulb? (Note: Never look directly at the sun!) Research to find more about the different elements that are in each light source.

Liquid Density Experiments

Do an experiement of density of different liquids. Which is denser, oil, corn syrup, or water? If you add all three to the same glass, which liquid will float on top of the others? Compare how well some objects (e.g., raisin, paper clip) float in each of the three substances. You can also experiment with colored water (e.g., red for hot, blue for cold) to find out whether different temperatures affect water density.

Why do objects that are the same size sometimes have different weights? The answer has to do with their density. An object's density is determined by comparing its mass to its volume. If you compare a rock and a cork that are the same size (they have equal volume), which is heavier? The rock is, because it has more mass. The rock is denser than the cork, then, because it has more mass in the same volume - this is due to the atomic structure of the elements, molecules, and compounds that make it up.

Liquids have density, too. You can perform several experiments with different types of liquids to determine which is more dense. These experiments can make a good science fair project; use them as a foundation and then come up with your own ideas of what to test.

Materials for Experiments 1 & 2

• 3 150 ml beakers (or use glass jars or clear plastic cups)
• 600 ml beaker (or use a large jar)
• water
• corn syrup
• vegetable oil
• food coloring
• several small objects - raisins, paperclips, pennies, small corks, etc.

Experiment 1: Sink or Swim

Question & hypothesis: Will a raisin, paperclip, penny, small cork, ball of paper, and other small objects sink or float if they are placed in water, corn syrup and vegetable oil? Write down what you think will happen when you place each object into the three different liquids.

Procedure:

1. Pour 150 ml of water into beaker #1, 150 ml of corn syrup into beaker #2, and 150 ml of vegetable oil into beaker #3. (If you are using glass jars, use 2/3 cup of liquid, which is approximately 150 ml.)
2. Gently set a raisin in each beaker. Does it sink or float? Write down what happens to the raisin in each beaker.
3. Take the raisins out of the beakers and try a different object, such as a paperclip or cork. Record what happens in each beaker.

Conclusions: Were your predictions right? Did the raisins and other objects sink and float when you expected them to? Did they float in one liquid and sink in another? Why do you think they acted the way they did?

The denser a liquid is, the easier it is for an object to float on it. If one of your objects floated in the corn syrup but sank in the water, what does that tell you about the densities of water and corn syrup? Take the experiment a step further to find out more.

Experiment 2: Mix it up

Question & hypothesis: Which is the most dense: water, corn syrup, or vegetable oil? Which is the least dense? Based on your results from experiment #1, predict which liquid you think is the most dense and which you think is the least dense.

Procedure:

1. Place a few drops of food coloring into the beaker of water so you will be able to tell it apart from the other liquids. (This is not necessary if you are using dark corn syrup.)
2. Carefully pour each of the liquids into a 600 ml beaker or a large jar. Let them settle.
3. What happened? Did the three liquids mix together or separate into layers? Which liquid is at the bottom of the jar? Which is at the top?

Conclusions: Was your prediction right? If so, the liquid you thought was densest should be at the bottom of the jar. The next dense will float on top of that, and the least dense will float at the very top.

Now you know how the densities of the three liquids compare to each other. If you want to find out the approximate density of each, you can calculate it using this formula: Density = Mass/Volume. On Earth we measure mass (how much of a substance there is) by calculating weight (how heavy it is). Weigh each liquid in grams (make sure you subtract the weight of the beaker!) and then divide that number by the volume (number of milliliters) of the liquid. The answer is density in grams per milliliter. (Your answer will be more exact if you use a graduated cylinder instead of a beaker to measure the volume and weigh the liquid.)

Materials for Experiments 3 & 4

• 3 150 ml beakers (or use glass jars or clear plastic cups)
• 10 ml graduated cylinder (or a tall, narrow glass)
• pipet
• water
• salt
• sugar

Experiment 3: Hot and Cold

You've found out how the density of water compares to the density of oil and corn syrup; now see if you can change the density of water itself!

Question & hypothesis: Does temperature change the density of water? Write down what you think will happen when you mix cold water and hot water.

Procedure:

1. Fill two beakers with 150 ml (2/3 cup) of water. Put several drops of blue food coloring in one beaker, and several drops of red in the second.
2. Add a handful of ice to the blue water and put it in the refrigerator for a few minutes. Put the red beaker in the microwave for a minute.
3. Take the blue beaker out of the fridge and the red beaker out of the microwave. Pour some of the blue water into the 10 ml graduated cylinder or narrow glass. Using a pipet, slowly add red water a drop at a time and watch what happens. (This part may take a little practice--if you add the red water too fast you will force the colors to mix. Hold the pipet near the surface of the water and keep trying until you get it!)

Conclusions: Was your prediction right? What happened to the colored water? Did it stay in layers? Which layer was on the bottom? On the top? What does this tell you about the density of hot water compared to cold water? What would happen if you left the cylinder out until the cold water warmed up and the hot water cooled off? Do more experimentation to find out!

Experiment 4: Salty or Sweet

Now you know that temperature can affect the density of water. In this part of the experiment, test to see if adding salt or sugar will make water more dense.

Question & hypothesis: Will adding salt make water more dense? Will adding sugar make water more dense? Which is denser, sugar water or salt water? Write down what you think will happen to the density of water if you add salt or sugar.

Procedure:

1. Fill three beakers with 150 ml (2/3 cup) of water. Add food coloring to make blue, red, and green water.
2. Add 2 teaspoons of salt to the red beaker and stir until the salt is dissolved. Add 2 teaspoons of sugar to the blue water and stir until it is dissolved.
3. Try putting a raisin in each of the beakers. Does it float? Remove the raisins with a spoon.
4. Pour some of the red (salty) water into the graduated cylinder. Using the pipet, slowly add the blue (sugar) water one or two drops at a time. Record which sinks to the bottom and which floats on top.
5. Add the green (pure) water drop-by-drop to the other two and record what happens.

Conclusions: Were your predictions correct? Did adding salt and sugar to the water make the water more dense or less dense? Which was more dense, the salt water or the sugar water?

What is the Scientific Method?

If you're wondering for the tenth time, "What is the scientific method?," wonder no longer! The scientific method is a great tool for scientific discovery and for coming up with sound scientific conclusions. You'll use it constantly in science fair projects as well as basic experiments. This method can be broken down into five simplified steps. You may not need every step for every experiment you do, but as a whole these provide a solid foundation for science exploration.

Define the problem. Decide what you want to find out from your project. What aspects of a science topic interest you? For example, you might wonder, "How does lack of sunlight affect plant growth?" You can use preliminary research to narrow down or define your problem if you need to.

Observe/Gather data. In this step, collect information related to the problem. You might do this by reading science books and magazines on your topic or by doing research on the internet. (Look for university or government sites.) You can also talk to people who work in a related scientific field and are knowledgeable about your topic.

Think about it/Predict. The special name for this is hypothesizing. Predict an answer to your problem, based on the information you found. Look for patterns in the data that might lead to a reasonable prediction. You might form a hypothesis that "even one hour less sunlight per day will affect the growth of a sprouting bean plant."

Experimenting. This is the really hands-on part, when you design, perform, and analyze experiments to test your hypothesis. By repeating the experiment, you'll have more results to compare and draw accurate conclusions from. This principle applies even when completing experiments from a curriculum.

Controlling variables is essential for getting accurate results. Variables for a plant growth experiment include kind of seed, amount of water, position in sun, as well as amount of light. If you are testing the effect of less light, this is a changing variable. At the same time, make sure constant variables do not change between experiments: all the bean sprouts came from the same packet of seeds, you give each plant an equal amount of water, and they are placed in the same position outside.

Another key is multiple test subjects. Don't cover just one bean sprout with a paper bag for an hour and compare it to another bean sprout. Use more than one plant as your test subject, and use more than one plant as your control group of "normal" plants.

Forming conclusions. If your experiments turn out as forecasted, then your predictions were probably based on sound scientific principles. If they were off target, evaluate your data and start again with a refined hypothesis! Usually if something goes wrong, you should check your variables.

Where do scientists go from there? After a good conclusion has been tested often enough, with the same results each time, it becomes a theory - a model or explanation of a scientific concept. A theory that has been tested often enough with the same results becomes a scientific law. However, this does not mean the law is absolutely certain; it just has a lot of evidence to support it.

The scientific method hasn't always been around, but the mathematician and natural philosopher Roger Bacon used something like it back in the 1200s. He emphasized the importance of experimentation to verify a hypothesis. As his method gained followers, the way people went about science began to change. They used inductive rather than deductive reasoning. Deductive reasoning looks at something general and then moves to conclusions about a specific example, whereas inductive reasoning looks at specific ideas or situations and from there draws conclusions about a whole. Basically, inductive reasoning applies specific evidence to a much broader related idea. The scientific method does the same thing by studying the specifics in detail and then drawing a general conclusion.