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.
Nail polish marbling is tons of fun and yields stunning results. However, it takes some eye-hand coordination, practice and patience, so I’d recommend it for ages 10 and up. My 11 YO loved it!
Hint: You’ll have to work reasonably fast for good results. Gloves are a must, and do this in a well-ventilated area to avoid breathing too many nail polish fumes.
-eggs with the raw yolks and whites blown out (We poked generous holes in each end of our eggs using a thumb tack, scrambled the inside with a toothpick and used syringes and balloon pumps to blow out the raw whites and yolks. It takes patience, and you’ll lose a few eggs to cracks.)
-a container that can be thrown away
-nail polish in two or more colors
1. Fill your container 3/4 full of water.
2. Drip nail polish, a drop at a time into the center of the water. Each drop should be in the center of the one before. Don’t worry if they spread out, just keep adding more. You’ll have to work fast, or the polish will dry on top of the water. It may take practice.
3. Use tip of the toothpick to draw designs in the polish. Start by pulling it out from the center or pushing it into the center.
4. When the design is ready, roll it onto your egg like you’re rolling a bandage around an ankle. Try to keep in smooth and in a single layer. If it looks bad, try another one. You’ll get the hang of it!
5. Put the marbled egg on an egg carton to dry.
The science behind the fun: Nail polish is less dense than water and floats on top of it. It contains a solvent called acetate that evaporates very quickly into the air, drying out the polish.
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.
If you prefer not to let your kids mix up slime using powdered detergent, contact lens solution containing boric acid makes a good Borax substitute, when combined with baking soda and glue. (Note: Most liquid laundry detergents in recipes for “Borax-free” slime contain Borax.)
What’s the science behind the fun? To make slime, you need a chemical called a crosslinker to make all of the glue molecules stick together. When you use contact lens solution, the boric acid in contact solution combines with baking soda to make borate, the same crosslinking solution that Borax contains.
To make Borax powder-free slime, just add a pinch or two of baking soda per ounce of glue (around 1 tsp per bottle of clear glue), stir, add food coloring or glitter and then keep adding contact lens solution and stirring until the glue isn’t sticky any more. You can add water to the glue before adding the contact solution to change the consistency of the slime.
You can find more slime recipes here.
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.
To make a battery, you need two oppositely charged electrodes (materials that pass electrical current from one thing to another) and an electrolyte (a liquid that allows charged atoms to travel through it.)
If you stick a zinc (galvanized) nail and a copper wire side by side into a lemon, but not touching each other, they act as electrodes. The lemon juice acts as the electrolyte.
A chemical reactions occurs between the zinc electrode and the acidic lemon juice, resulting in a second chemical reaction at the copper electrode. If you attach the two electrodes to a metal wire, electrons from the chemical reaction will flow through the wire from the zinc to the copper, creating an electric current. We used a tool called a mutimeter to connect the two electrodes and measure the current flowing through the wire.
To make a lemon battery, push a zinc nail and a piece of copper into a lemon, side by side, but not touching. You can use a copper wire or a penny.
Touch the two ends of a multimeter to each of the electrodes to see how much current you’re generating. (See image below.)
Test how changing the distance between the two electrodes changes the current. What else could you try?
(Re-post from April 14, 2016)
I love traditional tie-dye, but it’s fun to do this experiment that uses permanent markers and rubbing alcohol to make bright, gorgeous designs that mimic tie-dye, more easily, and with less mess.
This experiment was created by Bob Becker, a chemistry and AP chemistry teacher at Kirkwood High School in Kirkwood, MO. (To find a few of the original experiments I invented, check out Frankenworms, Sugar Cube Fizz Bombs, Homemade Window Stickies, Foaming Slime, and Cornstarch Frescos.)
Here’s a video from my YouTube channel on how to do this experiment, so kids can “watch and do.”
To play with permanent marker tie dye, you’ll need:
-permanent markers (like Sharpies)
-cotton items to decorate, like tee-shirts, socks, or dish towels
-rubbing alcohol (isopropanol)*Read warning labels. Parental supervision is required, since rubbing alcohol is poisonous if swallowed. Do this experiment in a well-ventilated area, and do not expose your artwork to heat until is is COMPLETELY dry, since rubbing alcohol and its fumes are flammable.
-containers like plastic cups or jars
To make your designs, stretch the cotton over the mouth of a jar or cup and secure it with rubber bands. (See video above.)
Use permanent markers to make several dime-sized dots of different colors on the stretched cotton.
Slowly drip rubbing alcohol onto the spots of color until the alcohol starts to soak outward, carrying the ink with it.
Allow your design to dry overnight. When completely dry, hang your shirt in the sun, or put it in the dryer for 15 minutes to set the color. Wash separately from other clothes, just in case!
The Science Behind the Fun: 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. Small pigment molecules move faster than big ones, so the colors sometimes separate into their different color components as they move through the cloth. The alcohol evaporates into the air, leaving the ink in the fabric, and since it is still insoluable in water, it won’t come out when you wash it.
Enrichment: What happens if you draw lines, concentric circles or different shapes on your designs? Can you layer colors and watch them separate? What if you add rubbing alcohol next to the color, instead of directly on it? How many drops of alcohol do you have to add to a dime-sized color spot before it starts to expand?
Remember this homemade snow candy from Laura Ingalls Wilder’s classic “Little House in the Big Woods?” You can make the same amazing maple treats using heat evaporation and quick cooling in the snow, or on crushed ice cubes.
Here’s how to make the candy, along with some candy-making science, straight from the pages of my new book, “Outdoor Science Lab for Kids,” which you can order from your favorite book retailer by clicking here.
-1 cup pure maple syrup
-fresh, clean snow
Safety Tips and Hints:
-Hot sugar syrup can cause burns. This experiment must be done with adult supervision.
-Allow candy to cool completely before tasting.
-Only use pure maple syrup for the best results.
Step 1: Go outside and scout out a spot with some clean snow several inches deep for making your candy. Alternately, collect and pack down a few inches of fresh snow in a large, flat container, like a casserole dish. (You can use crushed ice cubes if you don’t have snow.)
Step 2. Boil the maple syrup in saucepan, stirring constantly until it reaches around 235-240 degrees F (soft ball stage.)
Step 3. Remove the maple syrup from the heat and carefully pour it into a heat-resistant container with a spout, like a Pyrex measuring cup.
Step 4. Pour wiggly candy lines into the snow to freeze them into shape.
Step 5. When you’re done, remove the candy from the snow with a fork.
Step 6. Eat your candy right away, or let it warm up and wind it around sticks or skewers to make maple lollipops. Enjoy!
The Science Behind the Fun:
Maple syrup is made from watery tree sap boiled to evaporate most of the moisture it contains when it’s first tapped from a tree. Following evaporation, the syrup that remains is mostly made up of a sugar called sucrose, but it also contains smaller amounts of glucose and fructose.
Naturally, other organic compounds are also present in tree sap, giving syrup from different areas unique flavors. Syrup collected earlier in spring when it is cold tend to be light in color and have a mild flavor. As the days get warmer, microbes ferment some of the sugar in the syrup, making it darker and giving it a more robust taste.
In this experiment, you heat maple syrup, evaporating even more water. A super saturated solution forms, which holds more sugar molecules in the liquid than would be possible if you evaporated the water at room temperature.
When you pour the supersaturated sugar into the snow, it cools quickly, forming some sugar crystals to give the maple candy a soft, semi-solid consistency. Heating the syrup to a higher temperature will evaporate more water, resulting in even more crystal formation in the cooled syrup, making it harder to bite. If you carefully evaporate all of the water from maple syrup, you’ll be left with pure maple sugar crystals.
-Try collecting some syrup from your pan at several different temperatures and compare the resulting snow candy for texture, color and consistency.
-Can you do the same experiment with other sugar syrups, like molasses or corn syrup?
-Try to make maple sugar.
Buying gifts is fine, but it’s more fun to make them. This year, we decided to make botanical gifts for the adults on our list, and slime kits for the kids.
To make a slime kit, you’ll need:
-glitter glue (optional)
-Borax laundry detergent
-small plastic sample cups or paper cups (optional)
-jars with lids
-a small plastic bin or shoe box
-extra glitter (optional)
Label the jars and fill as follows:
- Bouncy Ball Mix (fill with glue)
- Slime Mix (fill with equal parts glue and water, mixed well)
- Borax detergent (fill with powdered detergent)
- Cross-Linking Solution (leave empty)
- optional-Sparkly Bouncy Ball mix (fill with glitter glue)
- optional-Sparkly Slime Mix (fill with equal parts water and glitter glue, mixed well)
Make an instruction sheet for the kit. (Print out the info below, or copy it onto a card.)
To make slime:
- Fill Cross-Linking Solution container with warm water. Add about 2 tsp Borax per 1/2 cup water to the container. Mix well. (Don’t worry if all the Borax doesn’t dissolve!)
- Add a few spoonfuls of Ball Mix or Slime Mix to a small plastic cup or paper cup.
- Add a drop or two of food coloring to the cup. Stir.
- Add 3 spoonfuls of the Cross-Linking Solution to your ball mix or slime mix and stir well.
- If the slime still feels too sticky, add a little more Cross-Linking Solution.
- Remove your completed slime from the cup.
The Science Behind the Fun:
Glue is a polymer, which is a long chain of molecules linked together, like a chemical chain. The polymer formed by water and glue is called polyvinyl acetate.
The Borax solution is called a cross-linking substance, and it makes the glue polymer chains stick to each other. Eventually, all the chains are bound together and no more cross-linking solution can be taken up.
To finish the slime kit, fill the plastic bin with the ingredients you put together, including jars of ingredients, instructions, plastic spoons, and mixing cups (optional.)
(Adapted from Kitchen Science Lab for Kids)
Grab an extra bag of cranberries this Thankgiving! Kids can use it to reveal invisible messages they write with baking soda and water.
-around 2 cups of cranberries
-small paintbrush, Q-tip, or lollipop stick
Safety tips and Hints:
Boiling the berries should be done by an adult. Keep the lid on the pan, since the air pockets that make cranberries float can also make them explode. Kids can take over once the juice is cool.
When playing with cranberry juice, aprons or old clothes are a good idea, since it stains!
Step 1. Cut a cranberry in half and observe the air pockets that make it float.
Step 2. Boil the cranberries in about three cups of water for 15 to 20 minutes, covered. Listen for popping sounds as the air in the cranberries heats up and they explode.
Step 3. Crush the cooked berries and push the liquid through a sieve or colander to collect the concentrated cranberry juice.
Step 4. Allow the juice to cool and pour it into a casserole dish or cake pan big enough to hold a piece of paper. If your cranberry juice seems thick and syrupy, add a little water, so that it’s thin enough to soak into paper!
Step 5. Test the paper you want to use by cutting a small piece and soaking it in the cranberry juice. If it stays pink, it will work, but if it turns blue or gray, try some other paper.
Step 6. Add a few teaspoons of baking soda to 1/3 cup of warm water and stir well. Don’t worry if you can still see some baking soda.
Step 7. Using a Q-tip, paintbrush, or a homemade writing tool, use the baking soda solution as ink to write a message on your paper. It may take a little practice, so don’t get frustrated.
Step 8. Let your message air dry, or speed things up with a blow dryer.
Step 9. To reveal your message, place your paper in the cranberry juice and see what happens!
*What other natural acid/base indicators could you use to do this experiment? What else could you use as ink.
The Science Behind the Fun:
Cranberries contain pigments called anthocyanins (an-tho-SY-a-nins,) which give them their bright color. In nature, these pigments attract birds and other animals to fruit. This is important because animals eat the berries and spread plants seeds from one place to another.
These pigments, called flavanoids, change color when they come in contact with acids and bases. Cranberry juice is very acidic, and the pigment is pink in acids, but when you add it to a base, it turns purple or blue.
Baking soda is a base, so your baking soda message will turn blue when it comes into contact with the pigments in the cranberry juice. Eventually, when enough cranberry juice soaks into the paper, it will dilute the baking soda, turning the pigment back to red and your message will disappear!
There are over 300 kinds of anthocyanins which are found in many fruits and vegetables including blueberries, red cabbage, grapes and blueberries. Scientists believe they may have many health benefits.