Sodium alginate (Say it like you say algae!) is a substance found in the cell walls of brown algae, including seaweeds and kelp. Its rubbery, gel-like consistency may be important for the flexibility of seaweed, which gets tossed around on ocean waves.
Here on dry land, you can use sodium alginate to make edible balloon-like blobs that are liquid in the middle. We can thank scientists for this delicious project, since they discovered that a chemical reaction between sodium alginate and calcium causes the alginate to polymerize, or form a gel. In this experiment, the gel forms on the outside of a sodium alginate blob, where the chemical reaction is taking place. The inside of the blob remains liquid!
No heat is required for this experiment, making it safe and fun for all ages!
Sodium alginate and calcium lactate can be tricky to find at the grocery store, so you’ll probably have to order them online. But they’re not very expensive, and you’ll have lots of fun playing with them!
-a blender or hand blender (parental supervision required for small children)
-1/2 tsp sodium alginate
-2 tsp calcium lactate
-flavored drink drops, like Kool-Aid or Tang (optional)
You can try making these with juice, but if there is any calcium in the juice, you may end up with foam in your blender, since it may start to polymerize the sodium alginate when you blend it in.
- Add 1 and 1/2 cup water to the blender.
- To the water, add 1/2 tsp. sodium alginate.
- Blend for about a minute, and let rest for 15 or 20 minutes, until the bubbles are gone.
- If you want to add flavor, divide the sodium alginate solution into small containers and stir in the flavor, like a squirt of Kool-Aid liquid.
- Add 4 cups of water to a clean, clear glass bowl or container.
- To the water, add 2 tsp. calcium lactate and mix until completely dissolved. This is your calcium lactate “bath.”
- Fill a spoon, like a tablespoon, with the sodium alginate solution, and slowly lower it down into the calcium lactate bath. You’ll see a gel begin to form. Gently turn the spoon so the sodium alginate falls off the spoon and into the calcium lactate.
- After about 30 seconds, you’ll be able to see a pale blob in the water. Leave it there for three or four minutes. You can make several edible balloons at once.
- When the blobs are ready, use a spoon to carefully remove them from the bath and put them in a clean bowl of water for a few seconds to rinse them off.
- Put your edible balloons on a plate and taste them. What do you think?
Now that you know how to polymerize sodium alginate with calcium, what else could you try? Can you make a foam in the blender? Can you make gummy worms in the bath using the rest of your sodium alginate solution? Can you invent something entirely new??? Try it!
Thank you to Andrew Schloss’s book Amazing (Mostly) Edible Science for the experiment inspiration! Adding the Kool-Aid and Tang drops to add a little flavor and color was our idea!
Looking for some Earth Day fun? 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.)
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.
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?
Spring is egg season. You may prefer dyed eggs, hard-boiled eggs, deviled eggs, or even dinosaur eggs. No matter what kind of eggs you like best, you’ll love these eggsperiments that let you play with the amazing architecture of eggs, dissolve their shells and even dye them with the pigments found in your refrigerator. Just click on experiments for directions and the science behind the fun!
Spring break is right around the corner!
Here are three experiments that will appear in my upcoming book Outdoor Science Lab for Kids (Quarry Books, June 2016) to keep get kids off screens and into some science. Click on the experiment name to go to my original blog post, instuctions and more about the science behind the fun.
Not only is it simple to make your own lip balm, it’s science!
I love this experiment so much that I feature it in my book “Outdoor Science Lab for Kids”, which will be out in June and can be pre-ordered now!
To make colored, flavored lip balm, you need to think cosmetics chemistry. Here’s the recipe, adapted from the book:
– coconut oil
– beeswax beads or grated beeswax
– microwavable bowl
– colorful liquid drink mix drops, like Kool-Aid drops or water flavoring
-small containers with lids to hold lip balm, like empty contact lens cases
-toothpicks for stirring
-Heating and pouring steps must be done by an adult or with adult supervision to avoid burns.
Step 1: Mix together two parts coconut oil to one part wax beads. (For example, 8 Tbs. coconut oil, 4 Tbs. wax bead.)
Step 2. Microwave mixture at 30 second intervals, stirring in between, until wax is completely melted and the solution is clear.
Step 3. Cool briefly. If the solution gets cloudy or turns white, reheat it.
Step 4. As the solution cools, add a drop or two of flavoring mix to the lip balm containers.
Step 5. Carefully pour some hot oil/wax mixture into one of the lip balm containers and stir with a toothpick. Continue stirring as the lip balm cools into a smooth paste. Repeat until you’ve filled all of your containers.
Step 6. When the lip balm has cooled completely, smooth it off using a popsicle stick or the back of a metal spoon warmed in hot water and dried off.
Step 7. Keep your lip balm, give some to your friends, or sell it at a lemonade stand!
The Science Behind the Fun (from Outdoor Science Lab for Kids):
“Coconut oil is actually a mixture of fats and oils that is somewhat solid at room temperature, but melts easily when it gets warm. In this lip balm concoction, it serves as a moisturizer called an emollient, which acts as a barrier to hold the natural moisture in your lips.
Beeswax melts at high temperatures, but solidifies at room temperature, thickening the lip balm.
Since oil and water don’t mix together easily, and your colorful flavor drops are mostly water, you have to keep stirring them into the cooling wax and oil mixture to form a suspension of tiny globs, called an emulsion. Once the lip balm has cooled, the wax helps hold the entire solution together so that the oil doesn’t separate out.”
This morning, we made kid-sized catapults on WCCO MidMorning (Minneapolis/St.Paul)!
It’s one of the new experiments in my upcoming book, Outdoor Science Lab for Kids: 52 Family-Friendly Experiments for the Yard, Garden, Playground and Parks.
I also brought along a marshmallow slingshot , and a brand new experiment…a paper airplane launcher!
Did you know you can use science to make amazing works of art in Jell-O? I created this experiment to make Star Wars Jell-O, but you can take it in whatever direction you want. Remember, you’ll need agar, lots of Jell-O and some coconut milk to start experimenting! If your agar figures break, you can fill in the cracks with more melted agar! I ordered the silicone Star Wars molds on Amazon.com.
Here’s the science part: Agar is a substance extracted from the cell walls of red algae. It’s often used in cooking and science experiments. Agar has a higher melting temperature than the gelatin used to make Jell-O. So, if you put a piece of agar gel into melted Jell-O, the agar won’t melt unless the Jell-O is really hot (about 150 degrees Fahrenheit or 65 degrees Celsius!) That means you can create works of agar art to embed in your favorite Jell-O. We used silicone molds, cookie cutters and a molecular gastronomy technique called oil spherification to make our agar decorations. To make the orbs using spherification, you simple drip coconut milk agar through cold oil, forming perfect spheres that solidify as they fall. We talked with Astronaut Abby on Kare11 Sunrise about how you could make these orbs in space. Click here to see the segment.
Vegetarians like to eat agar, since it’s made from algae and not animals. In labs, scientists use agar to make petri dishes for growing microorganisms, since it won’t melt at high temperatures in incubators. They also use it to make gels for electrophoresis, to separate DNA and RNA molecules by size!
*If you want to make white orbs from the coconut milk agar, you’ll need to plan ahead and chill tall jar or glass of vegetable oil in the freezer until it is thick and almost frozen. You’ll also need some squeeze bottles or clean eyedroppers.
Coconut Milk Agar -To create your white decorations and mini orbs, mix up this coconut milk agar dessert.
2 1/2 cups water
4 Tbs Agar flakes from Asian section of grocery store or COOP
1 cup coconut milk (not lowfat) Mix the coconut milk well before you measure it.
4 Tbs. sugar
In a sauce pan or the microwave, heat 4 Tbs. agar in 2 and 1/2 cups water until the agar is completely dissolved. Adult supervision required.
To the agar mixture, add 1 cup coconut milk and 4 Tbs. sugar. Mix Well. Pour into molds, pour into a pan to cut shapes out with cookie cutters, or pour some into a squeeze bottle to make white orbs.
Coconut Milk Orbs (optional cool science experiment
Slowly drip melted coconut milk agar (above) through ice-cold vegetable oil. As it fall through the oil, it should harden and form orbs. Collect the orbs with a slotted spoon and rinse before adding to your Jell-O.
Follow the directions on the package for the speed set method. If you make a double batch, pour half of it into the bottom of a large, glass casserole dish or bowl. If it’s a single batch, pour the whole thing in. If you made coconut milk orbs, put some in the melted Jell-O to see whether they float or sink. Let the Jell-O solidify and arrange your agar decorations on the Jell-O.
Make or remelt more Jell-O. When it’s cooled down a bit, pour it over your decorations to trap them in the Jell-O. You may want to leave them sticking out a little, or cover them completely with Jell-O over them for effect.
What else could you try? What Jell-O masterpiece can you create?
With the touch of her bare hands, “Frozen’s” Elsa coats the world with ice. It takes a little longer, but with your imagination, you can grow alum or Borax crystals on almost anything and make ordinary objects look extraordinary! (Directions for growing Borax crystals on pipe cleaners is near the bottom of this post. Borax crystals grow much faster than alum crystals and you can make snowflake ornaments overnight!)
We coated pipe-cleaner snowflakes, styrofoam snow people and even an evergreen branch with gorgeous ice-like alum crystals.
Here’s how to grow your own alum crystals:
Ingredients: alum (spice section of grocery store. 3 small containers for half recipe, 5 containers for 4 cup recipe. Alum is relatively expensive, so you might want to cut the recipe in half and crystallize smaller items! It’s cheaper to buy it in bulk at your local COOP.) glue, water, paintbrush,small items you’d like to coat with crystals.
1. Using a paintbrush, brush glue on the surface you want to “freeze”. One option is to twist 3 pieces of pipe cleaner together to make a snowflake. If you have beads, add them to your snowflake before crystallizing!
2. Before the glue dries, sprinkle the object with alum. These are your seeds for crystallization. Allow object to dry.
3.With adult supervision, dissolve about 1 1/4 cup alum in 4 cups in hot water (we use the microwave), reserving some alum to sprinkle on other objects you may want to make later. (One 1.9 oz. container of alum is around 1/4 cup, so you’ll need 5 of them.) Liquid will be cloudy and some crystals will sink to the bottom. This is your supersaturated alum solution.
4. Allow liquid to cool.
5. Suspend objects in alum solution until crystals are the size you’d like them to be. This may take an hour for small crystals or overnight for large one. Remove the crystals from the jar and dry your crystallized object. We grew big crystals on our snowflakes and then scraped them off the beads, but left them on the pipe cleaners.
6. To crystallize more objects, reheat alum solution, stir up crystals to dissolve as many as possible, and cool before adding the next thing to be “frozen.”
To make Borax crystals, dissolve 10 Tbs. Borax in 3 cups of hot water and immerse pipe cleaners cut and twisted into snowflake shapes in the liquid. You don’t even need seed crystals to do this, since the Borax crystals will form on the pipe cleaner fibers on their own!
The Science Behind the Fun: Some crystals, like alum, will form from supersaturated solutions, like the one you used in this experiment. A supersaturated solution is one that is forced to hold more atoms in water (or another solute) than it normally would. You can make these solutions using heat or pressure. Crystals can form when a supersaturated solutions encounters a “seed” atom or molecule, or another impurity in the solution (like a pipe cleaner fiber) causing the other atoms to come out of the solution and attach to the seed. The more molecules attach, the larger the crystal will grow. Here’s how to make rock candy with sugar crystals.
What else can you think of to crystallize?
There are few gifts that are more fun (and less expensive) than a homemade science kit. Give a kid a bottle of vinegar and a box of baking soda and you’ll make their day. Throw in a bottle of Diet Coke and some Mentos mints, and you may be their favorite person ever. Make a kit for your kids or grand kids. Make one for your favorite niece or nephew. Encourage kids to make kits for friends and siblings. Make one for yourself!
When kids do science at home, there are no rules, there are no time limits, and no one is judging their results. It’s the perfect opportunity for them to explore, make guesses about what will happen and try new things. In other words, they’re learning to be creative. What could be better than that?
Below are some ideas for great items to include in your kit. I’ve highlighted links to the experiments on my website (just click on the blue experiment name) in case you want to print out directions to add to your kit.
You can also find these experiments, and more, in my book Kitchen Science Lab for Kids (available wherever books are sold online and in stores), on my free KidScience app for iPhones/iPads/iPods and on my Kitchen Pantry Scientist YouTube channel!
composition book: Makes a great science notebook to draw, record, and tape photos of experiments into.
clear plastic cups to use as test tubes and beakers
measuring spoons and cups
school glue for making Mad Scientist’s Green Slime
Borax detergent to use as a cross-linker for the Green Slime
gummy worms to transform into Frankenworms
baking soda: Can be used for a number of experiments like fizzy balloons and magic potion. Mix with vinegar to make carbon dioxide bubbles.
vinegar Great for fizzy balloons , alien monster eggs and magic potion.
balloons for fizzy balloons
dry yeast for yeast experiment
white coffee filters: can be used for magic marker chromatography, in place of a paper bag for a coffee-filter volcano or making red cabbage litmus paper.
cornstarch:Lets you play with Cornstarch Goo, a non-newtonian fluid. Here’s the video.
marshmallows with rubber bands and prescription bottle rings you have around the house can be used to make marshmallow catapults. My kids used theirs to make their own Angry Birds game.
Knox gelatin and beef bouillon cubes can be used to make petri plates for culturing microbes from around the house. You can also use the gelatin for cool osmosis experiments!
Food coloring Helps you learn about surface tension by making Tie Dye Milk. Here’s the video. You can also easily make colorful sugar-water gradients that illustrate liquid density!
Mentos mints will make a Mentos geyser when combined with a 2L bottle of Diet Coke.
drinking straws are great for NASA soda straw rockets and a carbon dioxide experiment.