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)
-squeeze bottle or syringe for popping boba*
You can make 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 (or calcium-free juice) 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, or 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.”
- To make edible water balloons, 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?
- *To make popping boba, add the fruit-flavored sodium alginate to a squeeze bottle or syringe. Drip the flavored sodium alginate into the calcium lactate as fairly large drops. It may take some practice to get uniform drops of the size you desire. When they’re solid enough to remove from the calcium lactate, rinse them gently and add them to your favorite drink. A small sieve works well for rinsing.
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! (This blog post was first published on KitchenPantryScientist.com on May 3rd, 2016 and revised to add popping boba July 24th, 2018.)
Happy #womenshistory month! If you don’t know who Rachel Carson is, you should! Share her story with your kids and who knows? Maybe they’ll be the next Rachel Carson! (I included environmental science project ideas in the video.)
Yesterday on Twin Cities Live, I demonstrated some fun botanical science projects for learners of all ages, including Vegetable Vampires and Leaf Chromatography.
This fun art/science project lets you transfer plant pigments to cloth, creating beautiful prints of your favorite leaves and flowers. It’s especially great for fall, when there are so many colorful leaves around.
-Fresh leaves and flowers (Dry leaves won’t work.)
-A hard, smooth pounding surface, like a wooden cutting board or carving board
-Wax paper or plastic wrap
-Mallets or hammers
-Untextured cotton cloth, like a dishtowel. Heavy cloth works better than very thin cloth.
-*Alum and baking soda to treat cloth (This is optional. I don’t pre-treat my fabric, but the treatment step will help bond and preserve color, if you want to frame your prints. You can also buy fabric that’s pre-treated for dyeing.)
Safety tips: Protective eye wear is recommended. Young children should be supervised when using mallets and hammers.
What to do:
*If treating cloth: The day before you do the project, add 2 quarts water to a large pot. Add 1 Tb alum and 1 tsp baking soda to the water. Add the cotton and bring to a boil. Simmer for 2 hours, turn off heat and soak for at least two hours. Let fabric dry.
The next steps are the same, whether you’re using an untreated piece of cotton or treated cloth.
- Take a walk to collect colorful leaves and flowers. Choose plants that can be flattened. Flowers with huge centers, like coneflowers don’t work as well, but petals may be removed and pounded.
- Cover the pounding surface with waxed paper or plastic wrap.
- Cut a piece of cloth that will fit on the pounding surface when folded in half. Iron the fold.
- Open the cloth and lay it on the pounding surface. (See image above)
- Arrange leaves and flowers on the cloth.
- Fold the cloth over the plants and pound it with the hammer or mallet. If you’re using a hammer, pound more gently.
- Pound until you can see the forms of the leaves through the fabric. As the pigment leaks through, you’ll see the outlines of what you’re smashing. Hint: Hammers work better than mallets for fall leaves. For juicy leaves and flowers, use a mallet or hammer gently.
- When you’re finished pounding, unfold the fabric to reveal the print you created. Remove the leaves and petals.
- Label the image with plant names, enhance it with paint or markers, or leave nature’s design to speak for itself.
The Science Behind the Fun:
Pigments are compounds that give things color, and many of them are found in nature. Flowers, leave, fruits and vegetables are full of brilliant pigments. In this experiment, we transfer plant pigments to cloth by bursting plant cells using pressure from a hammer or mallet.
The green pigment found in leaves is called chlorophyll. In the fall, many trees stop making chlorophyll, and the red, yellow and orange pigments inside the leaves become visible.
Although you create a mirror image of leaves and flowers, you’ll notice that the color may be more intense on one side of the print. A waxy covering called a cuticle covers leaves, and is sometimes thicker on the top than on the underside of the leaf. It may affect the transfer of pigment to the cloth, making it easy to see structures like veins on the leaf print.
What parts of the leaf can you identify in the print you created?
This fun project from my book Outdoor Science Lab for Kids shows you how to collect and identify amazing arthropods using a net you make yourself. For more engaging outdoor experiments, you can order the book here, or anywhere else books are sold.
– sweep net or: two wire hangers, an old, light-colored pillowcase, scissors, pliers, long wooden broomstick or sturdy yardstick, and duct tape
– area with long grass
-large white piece of fabric, like an old sheet
– insect identification books (optional)
Safety Tips and Hints
- Don’t pick insects up with your bare hands, unless you know they don’t bite or sting.
- Ticks love tall grass. If there are ticks in your area, take precautions and do a tick check after your insects hunt.
Step 1: If you don’t have a sweep net, make one by straightening and twisting two wire hangers together. Form them into a loop, leaving about 3 inches (8cm) straight on either end. Cut about one third off of the open end of a pillow case and pull the mouth of the pillowcase over the wire loop. Tape it securely around the perimenter.
Step 2. Find an area with long grass and plants. Sweep with your net the same way you’d sweep a floor, but flip the open side of the net back and forth to capture insects in the grass.
Step 3. Close your net by flipping the bottom over the top and take it over to your large piece of fabric.
Step 4. Carefully dump the creatures you’ve collected onto the white fabric to inspect them. If you want a closer look, put an insect inside a jar with a loose lid.
Step 5. Count how many legs they have, how many body segments, look for antennae, wings and unique color. Record your observations in a notebook.
Step 6. Use insect identification books, or other means to identify what you’ve found.
Step 7. Keep a journal of the insects and arachnids you capture, the time of day, and where you found them.
The Science Behind the Fun:
When you sweep, chances are you’ll find lots of insects, which are arthropods with six legs. They often have wings, and their life cycle goes from egg to larva, to adult. Some insects, like butterflies, also go through a pupal stage, in which their bodies are significantly transformed. The antennae on their heads are sensory organs.
Tillandsia, also known as Air Plants, come in many shapes, sizes and colors. In nature, you’ll find them living in trees in warm places like South America. They collect moisture from the air and rain, rather than pulling it up via roots like most plants, so you can care for them with a weekly misting.
Pick up a few clear, hollow “decorate your own” ornaments, and you can use these living wonders to make unique homemade decorations. We’re giving them as gifts this year.
-clear ornaments with removable tops
-small Tillandsia that will fit through ornament tops (Air Plants are available at most nurseries. Ask for care instructions, if they have them.)
-needle nose pliars, or tweezers
Note: Choose plants that are small enough to fit through the openings of your ornament!
Mist your plants, or soak them in a bowl of clean water for 15 minutes or so, gently shake off the excess water, and carefully push them into the ornaments, bottom first so you don’t harm the plant. Put the top back on the ornament, leaving it loose enough for air to circulate.
Once a week or so, remove the top of the ornament and add some water. Coat the entire plant with water, pour out the excess and put the top back on. After the holidays, you can remove the plants with tweezers and move them to a new home in a vase, bowl or other clear container.
(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.
Here are ten quick and easy experiments to make your Halloween even more fun and memorable!
Click on these links for instructions on how to make:
Here are a few of my favorites!
You can find more experiments by scrolling down on my website!
Unlike the foaming green alien blood in the X-Files, the blood pulsing through our veins is red, thanks to iron-containing hemoglobin molecules loaded with life-giving oxygen.
To make fake blood that looks like real blood, you’ll need to concoct a mixture of liquid, thickeners and red pigment (tinted with blue and brown.) Kids will have a great time coming up with their own concoctions. Have a creative chemistry contest to see who can come up with the most realistic fake blood, or use it to make scary Halloween props.
Here’s a recipe to start with, but kids can work with smaller amounts and mix their blood in bowls, rather than a blender. Fake blood stains everything it touches, so be prepared for messy hands and wear old clothes! Naturally red plant pigments, like the ones in pomegranate juice and raspberry jam won’t stain fingers as much as food coloring and taste yummy. However, red food coloring will give you a more realistic color.
1/3 cup pomegranate juice (like POM) or fruit punch
2 Tbs corn starch
1 Tbs chocolate syrup (or 1 Tbs cocoa powder)
1 Tbs red food coloring
1 cup corn syrup
Tint with a tiny bit of blue food coloring. (optional)
Other ingredients to try: seedless raspberry jam, cocoa powder, Kool-Aid, Jell-O, flour, maple syrup
Here’s a fun TV segment where meteorologist Matt Brinkman was game enough to try out one of the blood capsules we made!
We made the edible blood capsules you see in the video by filling empty gelatin and vegetarian capsules with a mix of raspberry jelly, corn syrup and chocolate syrup.
Our eight Monarch caterpillars were in chrysalises when we returned from our vacation, and yesterday the first of them emerged! We were lucky enough to catch it on our iPhone time-lapse, which makes everything look faster than it actually happens. You’ll be amazed at how the butterfly pumps fluid from its body to expand its beautiful orange and black wings.
It’s almost summer! Whether you’re heading to the back yard, a park or a nature center, here are a few of our favorite free apps to enhance your next outdoor adventure…
Merlin Bird ID (free) The Cornell Lab of Ornithology makes it easy to identify that mystery bird in your back yard. http://merlin.allaboutbirds.org/
Leaf Snap: (free) Take a photo, identify a plant.http://leafsnap.com/
Bee Friendly: (free) Be a citizen scientist with this cool app that lets you identify and tracking pollinators like bees in your area. http://earthwatch.org/scientific-research/special-initiatives/bee-friend-your-garden
Starmap: iOS (Starmap Lite is free.) Use this app to easily find and identify constellations in the night sky. http://www.star-map.fr/
ISS Spotter: (free) It’s cool to watch the International Space Station fly across the horizon at night. This app will help you spot it, and even has an alarm so you don’t miss it. https://itunes.apple.com/us/app/iss-spotter/id523486350?mt=8
Magnificent : (free version) Magnify leaves, bugs and anything else you want to take a closer look at. http://habitualdigitalsoftware.com/