(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.
We have bags full of candy at our house, and I’d like to see them disappear as quickly as possible. Here are a few science experiments we tried, substituting candy for other ingredients:
Candy Chromatography: We put candy in water and used coffee filters to separate out the colors, via capillary action.
Candy-drinking plants? We dissolved candy in warm water and added white carnations with cut/split stems to see whether they’d change color as the flowers drew the water up into their petals.
Candy Vegetable Vampires: We tried the same experiment with Napa Cabbage, via the Vampire Vegetables experiment in Kitchen Science Lab for Kids.
We’re also going to freeze candy in ice and make Tie Dye milk with Skittles!
What could you try with your candy?
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!
We had a great time playing with dry ice on WCCO TV this morning. I showed viewers how to make spooky Halloween decorations (hot water, food coloring and dry ice), carbonate beverages, inflate a balloon, and even make a spoon “sing.”
Dry ice is literally really cool, which is why you have to wear gloves to handle it. It’s made from frozen carbon dioxide gas, and as it warms up, it goes from the solid to liquid state instantly, skipping being a liquid altogether in a process called sublimation. As it becomes a gas, it cools water molecules in the air around it, making fog. And if you add it to a liquid, it carbonates the liquid with bubbles.
To make dry ice, you have to get carbon dioxide gas really cold and put it under pressure so that it goes instantly from the gas phase to the solid phase in a process called deposition. Here’s a video of a machine that makes dry ice pellets:
If you’ve ever seen the X-Files, you know that foaming green alien blood is pretty scary.
It’s simple to use kitchen table chemistry to mix up your own batch of green alien blood with corn syrup, green food coloring, water and baking soda.
Just add vinegar (tell your friends it’s water) to make it foam.
2 Tbs corn syrup
1 tsp baking soda
green food coloring
1/2 tsp water
When you want to make your slime foam, add a few tsp of vinegar.
You could make the same thing with red food coloring and call it vampire blood!
The Science Behind the Fun: When you add baking soda (sodium bicarbonate) to vinegar (acetic acid), there’s a chemical reaction that creates carbon dioxide gas bubbles!
Experiment created by Liz Heinecke at KitchenPantryScientist.com
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.
I’ve always wanted to try paper marbling and knew there must be some science involved. So, we gave it a go, and the results were stunning!
We tried two methods: one with liquid starch (made from cornstarch) and tempera paint, and another with a marbling kit. Both worked well, but look very different.
The Science Behind the Fun: Water molecules like to stick together, a property which scientists call surface tension. This property allows very thin layers of ink to float on water, mixing in beautiful patterns when you break the surface tension with detergent, a tool like a paintbrush, or movement. To marble paper, you have to use dye or paint that floats on the water where it can be easily transferred to paper. Alternately, you can make the liquid underneath more dense than the dye or paint, to help the dye float.
When transferring the ink or paint designs, it helps to use paper that’s been coated with a chemical called a mordant, that combines with substances (usually dyes) to make large molecules that stay in one place. (Iodine is another mordant, which is used to stain bacteria.)
Here’s a video of my 10YO making designs using the pre-made marbling kit…(More info at the bottom of this post.)
Since I like to do experiments using non-toxic, inexpensive ingredients most people have on hand, we first tried a method that uses cornstarch to thicken the bottom liquid layer and tempera paint as the dye. It requires pre-treatment of paper, like inexpensive watercolor paper from Target, with the mordant aluminum sulfate (alum), which you can find at your local coop or grocery store.
-watercolor paper (cheap stuff from Target works just fine)
-two large, flat trays, like 9×13 pans
-2 tps. Alum (aluminum sulfate crystals)
-a sponge brush
-2 Tbs. corn starch
-tempura paint (the more colors, the merrier)
- Dissolve 2 tsp alum in 3/4 cup water. Avoid inhaling powder.
- Mark one side of your watercolor paper with an A and use a sponge brush to apply alum solution evenly to that side of the paper.
- Let the paper dry overnight, or speed drying with a blow dryer.
- Make a double recipe of liquid starch by dissolving 4 Tbs. corn starch in 1/2 cup cold water. Bring 6 cups water to a boil in a sauce pan. Add the cornstarch solution to the water, stir well and boil for 1 minute. Turn the heat to low and simmer for 2 more minutes, stirring occasionally.
- Pour 3 cups of the hot liquid starch into one 9×13 pan and let cool.
- Pour 3 cups of cold water into the other pan.
- Prepare paint by mixing tempura paint with water until it has the consistency of half-and-half or whole milk.
- When starch is cool, drip paint onto the surface of the starch using an eyedropper, or something similar. Rinse dropper between colors.
- Swirl paint, or use toothpicks to drag out patterns.
- Carefully place your paper on the paint, alum side-down. Let it sit for a minute or two.
- Carefully peel the paper off of the paint and gently place it, face up, in the water pan. Let it sink and move it back an forth gently to rinse off excess paint.
- Set the paper on a piece of newspaper to dry.
- Make more marble paper in the same paint pan. When you’re ready, repeat using the rest of the cornstarch.
The Innovation marbling kit (Boku-Undo Suminagashi) from DickBlick.com pictured below includes pre-made low density dyes that you drip onto a tiny floating disc of paper in a tray of water. It’s tons of fun and yields beautiful results. I got the kit at Blick art supplies, and used the paper they recommended, which may have been pre-treated with a mordant.
I learned how to make this fun, clay-based paint at the Minnesota State Fair’s Eco Experience Progress Center. It’s colored with natural pigments(pigments are molecules that give things color) and doesn’t give off the same chemical fumes as some of the paints you might find in a hardware store. I love the earthy colors you can mix up with elemental pigments like iron oxide, zinc oxide and black iron oxide. It’s fun to mix up a little blue too, using Ultramarine Blue dried pigments.
To make this paint, you’ll need:
EPK powdered clay (also called EPK Kaolin) -Can be ordered online. We got ours at continentalclay.com.
dried pigments, like the ones I mention above. -We got ours at dickblick.com
Safety tips: Check the warnings on dried pigments before you purchase them. Some are toxic and must be handled carefully. Avoid inhaling pigments.
To make your paint:
1. In a bowl, stir together 1/2 cup flour and 1/2 cup cold water. Mix well.
2. Add 1/4 cup hot water and mix well.
3. Add 1/4 cup EPK powdered clay and stir until smooth.
4. Continue adding flour and water until the paint has the consistency you want.
5. Divide the paint into several containers and mix in pigment for color.
6. Use paint on paper or canvas.
7. Paint may be stored in the refrigerator for a week or so.
We supersized the foaming slime experiment from Outdoor Science Lab for Kids to make a giant foaming slime volcano. And it was awesome!
One of the best things about doing science in the summer is that you can take the mess outdoors, and clean it up with a hose. So what are you waiting for? Grab the baking soda, vinegar, food coloring, cornstarch and balloons and head outside for some instant off-screen fun. Share photos of your experiments on Twitter and Instagram using the hashtag #ScienceMess!
Here are some ideas to get you started, but you can find lots more on this website and in my new book Outdoor Science Lab for Kids!
Sidewalk Frescoes with Cornstarch Goo
Solar Heat Beam
Have fun experimenting! And don’t forget to clean up your mess!