Here’s a fun optics experiment, based on one created in 1842 by Jean-Daniel Colladon, that you can do at home using a laser pointer and a bottle of water.
Parental supervision required. (Eye protection recommended for kids.) Never shine a laser pointer at or near eyes, as it can cause blindness.
Skullsinthestars.com has a well-written, detailed explanation of how light can be reflected in a transparent medium, like water.
This experiment is so awesome that our balloon-popping dog Heidi had to get in on the action! Try it, and you’ll see how much fun it is to play with the forces of physics using a blow drier and a ping pong ball or balloon.
Newton’s third law tells us that for every action, there is an equal and opposite reaction. As the air pushes up on the ball, the ball pushes back down on the air. Other forces are at work too, as pressure differences in the air column help the ball stay in the middle of the air flow.
It’s fun to track the weather, and you can create some cool meteorology instruments using stuff you have around the house. Here’s a great post by NOAA (The National Oceanic and Atmospheric Association) on how to make your own weather station.
It’s also fun and easy to do this cool convection current experiment, using warm and cold water to explore how air moves in Earth’s atmosphere.
To see how cold fronts move under warm fronts, you’ll need ice cube trays, water, blue and red food coloring and a clear container.
- Add water to an ice cube tray and add a few drops of blue food coloring to the water in each cube space. Freeze.
- Fill a clear container with room temperature water.
- Place one or two blue ice cube or two at one end of the container, and a few drops of red food coloring at the other end.
- Observe what happens.
The Science Behind the Fun:
Cold water(blue) is more dense than warm water and forces warmer water (red) to move up and over it.
This is similar to the way warm air is forced up when it collides with masses of cold air in the atmosphere. Warm air carries energy, and when there’s lots of moisture in the air, these collisions often result in thunderstorms.
Make a super-cool spinning toy using skateboard bearings, super glue and a little physics. Customize your design with a marker tie-dyed shoelace.
Warning: Not for recommended for kids under 5. Use adult supervision for super glue, sharp points, rubbing alcohol and glue gun.
-4 skateboard bearings (available online or at skateboard stores)
-superglue or Krazy Glue
-a white shoelace
-permanent markers, like Sharpies
-rubbing alcohol (isopropanol)
-a glue gun
1. Use a sharp point to remove the cover from one of the bearings so that you can see the ball bearings inside. (See image above.)
2. Cut a piece of paper 6cm x 6cm and draw an X from corner to corner.
3. Center the bearing with the cover removed in the middle of the X. Then, center the other 3 bearings around the one in the middle so that they’re evenly spaced. You can use a ruler to check spacing. (See image below.)
4. Add a single drop of super glue to the junction between each bearing to connect them. If you add too much, the spinner will stick to the paper. *Be careful not to get any glue onto the moving parts of the bearings.
5. When the glue is dry, carefully turn the spinner over and place another drop of glue at each junction.
6. When the glue is dry, prop the spinner up on its side and add glue to the junctions on the sides. (See image below.) Repeat on each side.
7. While the spinner glue is drying, make dots of permanent marker on the shoelace. In a well-ventilated area, suspend the shoelace over a tray or colander and drip rubbing alcohol onto it to make the colors run together. (See image.) Let it dry completely.
8. Use the glue gun to attach the shoelace to the outside edges of the spinner. Fill in gaps between the lace and bearings with hot glue.
9. Spin away!
The Science Behind the Fun:
If you look closely at a skateboard bearing there are only a few ball bearings connecting the center and the outside part that spins. This means that there’s very little friction, or rubbing, between the parts. If you spin the toy around the center bearing, that bearing is called the axis of rotation.
The three bearings on the outside of the spinner provide the rotating mass that gives the toy a property called angular momentum, which keeps it spinning until the frictional force from the ball bearings in the center slows it down.
Pigments are molecules that give things color. The pigments in permanent markers are trapped in ink compounds that are insoluable in water, which means that they won’t dissolve in water. However, if you add a solvent, like rubbing alcohol, or isopropanol, to permanent markers, it dissolves the ink. As the alcohol moves through the cloth you are decorating, it carries the pigments along with it.
With a brush, some batteries, a small motor and a few wires, it’s easy to create a robot that spins, bumps and buzzes around on any smooth surface.
-a small brush, like a vegetable brush or a cleaning brush
-two AA batteries
–battery holder for 2 AA batteries (optional)
-a small toy motor with lead wires and pencil eraser or small rubber stopper (or vibrating motor)
–battery clip (optional)
-zip ties (optional)
-electrical tape or duct tape
Make your bristlebot!
- Attach the motor to one end of the top of the brush. If it’s not a vibrating motor, stick a eraser or rubber stopper onto the spinning post to make it vibrate. Use a zip tie or duct tape to secure it. Make sure the spinning parts can rotate freely.
- Attach the battery holder to the top of the brush near the motor.
- Insert batteries in motor.
- Twist wires around the motor terminals and secure with tape. (These may be the wires on the battery clip, if you have one.)
- To start the motor, attach wires directly to the battery terminals, or to the battery clip and snap it onto the batteries.
- Place your robot on a smooth surface to see what happens.
Enrichment: Try different brush shapes, sizes and angles to see how they move. Does your robot spin in the same direction as the motor, or the opposite direction?
The Science Behind the Fun: In this experiment, you complete a battery-powered electrical circuit to spin a vibrating motor. The vibrations traveling through the bristles of the brush move your robot around on the floor.
Saturday April 22nd is Earth Day, so get outside and show our home planet some love! Whether you’re picking up trash or visiting a park, it’s always fun to throw some science into the mix.
Here are some of our favorite environmental science experiments. Just click on the experiment names for directions and photos. You can find more fun outdoor experiments in my books “Kitchen Science Lab for Kids” and “Outdoor Science Lab for Kids“ (Quarry Books.)
Homemade Sweep Nets: Make a sweep net from a pillowcase and a hanger to see what arthropods are hanging out in your favorite outdoor spaces.
Window Sprouts: Plant a bean in a plastic baggie with a damp paper towel to see how plants need only water and air to sprout roots and leaves. Here’s a short video demonstrating how to make a window garden.
Homemade Solar Oven: Using a pizza box, aluminum foil, plastic wrap, and newspaper, you can harness the sun’s energy to cook your own S’mores!
Nature Walk Bracelets: Wrap some duct tape around your wrist (inside out) and take a walk, sticking interesting natural objects like leaves and flowers to your bracelet. It’s a great way to get outdoors and engage with nature!
Carbon Dioxide and Ocean Acidity: See for yourself how the carbon dioxide in your own breath can make a water-based solution more acidic. It’s the same reason too much carbon dioxide in Earth’s atmosphere can be bad for our oceans.
Plant Transpiration: See how trees “sweat” in this survival science experiment.
Earthworm Experiment: Do you know what kind of earthworms are living in your back yard?
Composting: Be a composting detective. Bury some things in your back yard (away from power cables) and dig them up in a few months to see how they look. Composting reduces methane gas emissions (a greenhouse gas) from dumps.
Diffusion and Osmosis: See for yourself how the chemicals we add to water, put on our streets to melt ice, and spray on our lawns and crops can move into our soil, ground water, rivers, lakes and oceans.
Solar Water Purification: This project illustrates the greenhouse effect and is a fun “survival science” experiment. Requires hot sun and some patience!
Citizen Science: Don’t forget about all the real environmental research projects you can participate in through Citizen Science programs all around the world!
For mores activities and games, check out NASA’s Climate Kids website, to see a kid-friendly diagram of the water cycle, click here, or just get outside and enjoy the beautiful planet that sustains and nurtures us.
Want to take egg-dying up a notch the easy way? Marbling eggs using whipped cream and food coloring is a great project for little ones and the results are downright gorgeous!
Hint: Wear disposable glove to prevent your fingers from getting stained.
-hard boiled eggs
-a shallow container
-cool whip or whipped cream
-food coloring (neon, if you can get it)
-a chopstick or toothpick
1. Soak eggs in vinegar for 5 minutes.
2. Spread and smooth a layer of whipped cream across the bottom of the container and drip food coloring all over the whipped cream.
3. Swirl the drips into patterns using a toothpick or chopstick.
4. Remove eggs from vinegar, blot them with a paper towel and roll them through the food coloring. Put them on a plate to dry.
5. When the eggs are dry, wipe the excess whipped cream and color from the shells.
The science behind the fun: Food coloring is an acid dye, so the vinegar (acetic acid) helps it form chemical bonds with the egg shell, dying the egg.
It’s simple to make gorgeous marbled eggs using olive oil marbling. Simply dye your eggs with light coloed food coloring and then marble them with a darker color.
Hint: Wear gloves to avoid staining your fingers.
-2 cups of warm water in a bowl
-hard boiled eggs
-food coloring (We used Wilton Color Right food coloring: 2 drops blue mixed with one drop of yellow in about a cup of water to make robin’s egg colors, and brown for marbling.)
1. Make base dye by adding a few Tbs. vinegar to two cups of water. To this, add a few drops of food coloring. Lighter colors work best for the base.
2. Dye the hard boiled eggs in the base color until they are the desired shade. Let them dry.
3. To a small bowl, add 1/2 cup water, a Tbs. of vinegar, darker food coloring, and 1/2 tsp olive oil. Add more oil if you want less dark color when you marble. Oil shouldn’t cover the entire surface.
4. Swirl the oil with a toothpick or spoon and lower your egg into the water/oil mixture, swirling and spinning it. When you like the results, take it out and let it dry.
5.When the egg is dry, remove the excess oil with a paper towel.
The science behind the fun: Food coloring is an acid dye, so the vinegar (acetic acid) helps it bond to the egg shell. Oil is less dense than water and floats on top. When you put the egg in the oil-colored water mixture, the oil coats part of the egg, preventing it from being stained.
A homemade slime craze is sweeping the nation, and glue is becoming a limited resource as stores are swarmed by school kids on a quest to make the perfect goo.
I’ve posted recipes and videos for slime-making on this website and included one in “Kitchen Science Lab for Kids.” For my most recent book, “Outdoor Science Lab for Kids,” I invented a recipe for making slime that oozes from a bottle like a living thing.
But the other day, my 11-YO brought home a slime recipe featuring clear glue, baking soda, shaving cream and contact lens solution, and I was baffled. Which ingredient was the cross-linking chemical that would bind all of the glue molecules together into slime? I hadn’t had much luck using any cross-linker besides Borax laundry detergent.
Curiosity got the best of me, and a trip to Walgreens confirmed my suspicion that most contact lens solution contains boric acid, a cross-linking chemical related to Borax. In the glue aisle, I discovered a “Borax-free slime” recipe for slime made with Tide Free and Gentle. (Tide detergent does, in fact, contain the same chemical in Borax, so it’s not really Borax-free.)
A few days later, a friend called saying that the slime her kids were making with Borax and clear glue wasn’t turning out. That’s when I decided it was time for us to do some scientific sleuthing.
We tested two glues (clear glue and white school glue) with three cross-linking solutions (Borax laundry detergent, contact lens solution, and Tide Free and Gentle (which contains some Borax) to see how the end-products would differ.
Helpful hints: A bottle of glue contains 4 or 5 oz, which is a little more than half a cup. Mix glue with other ingredients BEFORE adding the cross-linker. Keep slime away from toddlers, as ingredients may be harmful if consumed. Always wash your hands after playing with slime.
Here’s what we found:
Traditional Borax Slime: Add equal parts glue and water (for example, one 5 oz bottle of glue+5 oz water.) Add glitter or food coloring. Dissolve a few spoonfuls of Borax in a cup of water to make a Borax solution. Add Borax solution to glue, a little at a time, until it no longer feels sticky.
-White school glue works best for this recipe and the result is smooth slime that can be rolled into long snakes.
-Clear glue doesn’t work well with this recipe and produces brittle slime. Save clear glue for the two recipes below.
Puffy Slime: Add 5 oz glue to a large bowl. Stir in 1/2 tsp baking soda, 1/4 cup shaving cream and glitter or food coloring. Mix well. Add contact lens solution as a crosslinker and stir. Keep adding contact lens solution until your slime is no longer sticky and knead slime until it has the desired consistency.
-White school glue works well with this recipe and results in a puffier, firmer product than clear glue. The slime has a strong shaving cream smell.
-Clear glue works well for this project and produces nice, smooth puffy slime that smells like shaving cream.
Tide Detergent Slime: Add 5 oz glue to a large bowl. Stir in 5 oz water and some glitter or food coloring. Add 1/4 cup of Tide Free and Clear laundry detergent. Mix well with a spoon and then hands to the desired consistency.
-White school glue works well with this recipe and the soap in the detergent makes tiny bubbles in the slime.
-Clear glue works well for this project and makes great , smooth slime that’s puffy from the soap in the detergent.
Try adding cornstarch, lotion, or anything else you can think of to perfect your recipe.
What are you waiting for? Go make some slime!
The Science Behind the Fun: A polymer is a long chain of repeating molecules, kind of like a string of pearls. The polymer in school glue is called polyvinyl acetate. Borax solution (sodium tetraborate) and boric acid (combined with baking soda to make borate), are cross-linking substances that make the polymer chains in glue stick together. As more and more chains stick together, they can’t move around and the solution gets thicker and thicker. Eventually, all the chains are bound together and no more Borax or boric acid solution can be incorporated into the slime.
Electrons (negatively charged particles) can flow through substances called conductors.
Graphite, used to make pencil lead, among other things, is a conductor and can be used to make a simple circuit on paper. A circuit is just a path for electrical current.
You have to do this experiment with a graphite pencil, rather than the kind you use at school, but you can pick them up at most art supply stores. You’ll also need a few small LED bulbs, 2 wires with alligator clips on either end, and a 9 volt battery.
Adult supervision recommended.
- Make a thick, black rectangle using a graphite pencil. We used a #9 graphite crayon.
- Hook the two wires up to the battery terminals.
- Clip the wire attached to the positive battery terminal to one wire of an LED bulb. (Don’t test it on the battery, or you may blow it out.)
4. Touch the un-attached LED wire to the other (left) side of the graphite bar.
5.Touch the alligator clip attached to the negative battery terminal to the right side of the graphite bar you drew.
6.If it doesn’t light, switch the positive alligator clip to the other wire of the LED bulb and try it again.
7. Move negative clip closer to the bulb. It should get brighter as you decrease the distance.