Want to get a taste of what it’s like to do a fresco painting?
Everyone from the ancient Minoans on the island of Crete, to Leonardo de Vinci, used this classic technique to paint into wet plaster made of lime, sand and clay. It was tricky, since you could only do a small area at a time, and the colors often got lighter as they dried.
Some frescos have lasted thousands of years as the result of the chemical reaction between the fresco materials and atmospheric carbon dioxide, which form calcium carbonate, the same material limestone is made of.
We created this experiment using a cool, fun-to-play with false fresco material made with a mixture of cornstarch and water. To make it more science-y, you can make it with cornstarch and red cabbage juice (instead of water) in order to paint with acids and bases!
Remember, all chopping and boiling of red cabbage should be done with adult supervision. The pH fresco won’t stain your driveway, but depending on the food coloring you use, the painted fresco may leave marks on concrete. You can also do this in small, flat containers to contain the mess, or if you want to do it indoors.
– 16 oz Corn starch
- scant 1 ½ red cabbage juice* for an acid/base fresco or scant 1 ½ cup water for painted fresco
- baking soda and vinegar for pH fresco
- food coloring for painted fresco
-toothpicks or small paintbrushes
*To make red cabbage juice, chop up ½ head of red cabbage, cover with water and boil for 10 minutes. Strain out cabbage. More detailed instructions here.
Step 1: Mix together the cornstarch and either water or red cabbage juice. The resulting mixture will look like glue. If it’s too dry and crumbly, just add a little more water until the consistency seems right. You should be able to roll it into a ball, but it should drip like a liquid when you stop moving it around.
Step 2. Pour some cornstarch mixture onto a clean, flat spot on a driveway or sidewalk. Alternately, you can pour it into a tray or pie tin.
Step 3. When the mixture has flattened out, let it sit for 5 or 10 minutes before you begin painting on it.
Step 4. For an acid/base fresco made with red cabbage juice, put vinegar in one cup and a few tablespoons baking soda mixed with ¼ cup water in a second cup. Use toothpicks or paint brushes to make designs on the cornstarch with the vinegar (turns red cabbage cornstarch mix pink) and baking soda solution (turns red cabbage cornstarch mix blue.) You can also paint on this fresco with food coloring.
For a painted fresco, put food coloring on a plate and use toothpicks or paintbrushes to paint designs on your fresco.
Step 5. Let your frescos dry to see what happens to the colors.
Step 6. Wash your frescos off the sidewalk using water from a hose.
The Science Behind the Fun:
The substance you made using water and cornstarch is called non-Newtonian, because it doesn’t act the way we expect a liquid to behave, and acts more like a solid if you stir it around or try to move it quickly.
When you use food coloring to paint on the cornstarch goo, the water-based pigments (color molecules) in the food coloring are absorbed into the cornstarch mixture, but they don’t travel diffuse very far since the cornstarch mixture is so thick. Here’s another diffusion experiment you can try called Homemade Window Stickies.
If you try the acid/base painting, you’ll see that vinegar, an acid, makes pink lines and baking soda solution, a base, makes blue or green lines. The pigment from the red cabbage juice is an acid-base indicator that changes shape depending on pH, absorbing light differently and changing color.
For some serious outdoor fun, try a little rocket science and parachute engineering. Click here to watch a demo and segment on rockets I did for Kare11 Sunrise (the top video on the page is metamorphosis, the bottom one is rockets)!
NASA works hard designing new parachutes to slow the descent of spacecraft so they aren’t damaged when they land on distant planets. It can be tricky, since parachutes depend on air resistance to slow the descent of their loads, and many planets have very little atmosphere.
Here on Earth, you can design and test parachutes for our terrestrial atmosphere using produce bags, glue dots and string attached to a water rocket, to see what works best! Click here for detailed instructions on making a water rocket!
You’ll need a bike pump, an empty 1L plastic bottle, a cork that fits the bottle, cut in half, an inflation needle, lightweight plastic bags, like produce bags, string or twine, and glue dots (optional)
1. Make a water rocket. Directions for assembling the rocket are here: http://kitchenpantryscientist.com/simple-water-rockets/
2. Cut produce bags into large squares.
3. Cut 4 or more strings to attach the produce bag parachute to the rocket. You can use kitchen twine, yarn or embroidery thread.
4. Use glue dots to firmly attach the strings to the plastic, and duct taping the parachutes onto 1 liter bottles. If you don’t have glue dots, punch holes in the corners of your parachute and tie the string on.
Safety goggles are required for this experiment!
6. Once you’ve made a parachute and attached it to a bottle, fill the bottle with 3-4 inches of water and plug it with a cork that’s been cut in half and impaled with a ball inflation needle.
7. Put on your safety goggles, attach the needle to a bike pump, set the bottle in a box or container so the bottom of the bottle is pointing up and away from you with the parachute positioned over the bottle (see photo), and start pumping!
What happens? As air pressure builds in the bottle, it pushes the cork and water down towards Earth, and sends the rocket in the opposite direction. Gravity pulls the empty bottle back to Earth, but the open parachute attached to it has a large surface area, which increases air resistance and adds a huge amount of drag to the falling rocket, slowing its fall.
The shape of the parachute, the length of the strings, and even the material the parachute is made from all affect how air moves around it and how well it slows the fall of an object. Adding holes to the parachute to help control air movement can also affect how well it works. It may take several tries to get your parachute to work, so don’t get frustrated! Just keep re-engineering it!
Have fun rocketing!
Got sugar cubes? Lemons? Baking Soda? You can make sugar cube fizz bombs! Click here for directions for this fun experiment I created for Imperial Sugar to take your lemonade stand up a notch. All the kids will want to try it!
Between working on a follow-up to Kitchen Science Lab for Kids (which involves testing, writing up and photographing 52 experiments), driving my kids around to camps and sports, and doing science outreach at libraries, bookstores and on TV, I’m finding it hard to keep up. Here’s a short video on how to make tie-dye milk (a surface tension experiment), which I did on WCCO Mid Morning show last week and forgot to post!
Luckily, between all the camps and activities, the kids and I are having fun digging in the dirt, blowing giant bubbles, and watching tadpoles and monarch caterpillars go through metamorphosis!
What science experiments are you doing this summer? It’s a great time to take science outdoors!
Here are some of our favorites:
Hungry? Build a solar oven from a pizza box and bake s’mores.
Stand on eggs or throw them as hard as you can without breaking them. You can always clean up mistakes with your hose!
And no summer would be complete at our house without an epic marshmallow shooting competition. You’ll even learn some physics!
From surface tension to evaporation, science come into play every time you blow a bubble.
Water molecules like to stick to each other , and scientists call this sticky, elastic tendency “surface tension.” Soap molecules, have a hydrophobic (water-hating) end and (hydrophilic) a water-loving end and can lower the surface tension of water. When you blow a bubble, you create a thin film of water molecules sandwiched between two layers of soap molecules, with their water-loving ends pointing toward the water, and their water-hating ends pointing out into the air.
As you might guess, the air pressure inside the elastic soapy sandwich layers of a bubble is slightly higher than the air pressure outside the bubble. Bubbles strive to be round, since the forces of surface tension rearrange their molecular structure to make them have the least amount of surface area possible, and of all three dimensional shapes, a sphere has the lowest surface area. Other forces, like your moving breath or a breeze can affect the shape of bubbles as well.
The thickness of the water/soap molecule is always changing slightly as the water layer evaporates, and light is hitting the soap layers from many angles, causing light waves to bounce around and interfere with each other, giving the bubble a multitude of colors.
Try making these giant bubbles at home this summer! They’re a blast! (It works best a day when it’s not too windy, and bubbles love humid days!)
To make your own giant bubble wand, you’ll need:
-Around 54 inches of cotton kitchen twine
-two sticks 1-3 feet long
-a metal washer
1. Tie string to the end of one stick.
2. Put a washer on the string and tie it to the end of the other stick so the washer is hanging in-between on around 36 inches of string. (See photo.) Tie remaining 18 inches of string to the end of the first stick. See photo!
For the bubbles:
-6 cups distilled or purified water
-1/2 cup cornstarch
-1 Tbs. baking powder
-1 Tbs. glycerine (Optional. Available at most pharmacies.)
-1/2 cup blue Dawn. The type of detergent can literally make or break your giant bubbles. Dawn Ultra (not concentrated) or Dawn Pro are highly recommended. We used Dawn Ultra, which is available at Target.
1. Mix water and cornstarch. Add remaining ingredients and mix well without whipping up tiny bubbles. Use immediately, or stir again and use after an hour or so.
2. With the two sticks parallel and together, dip bubble wand into mixture, immersing all the string completely.
3. Pull the string up out of the bubble mix and pull them apart slowly so that you form a string triangle with bubble in the middle.
4. Move the wands or blow bubbles with your breath. You can “close” the bubbles by moving the sticks together to close the gap between strings.
What else could you try?
-Make another wand with longer or shorter string. How does it affect your bubbles?
-Try different recipes to see if you can improve the bubbles. Do other dish soaps work as well?
-Can you add scent to the bubbles, like vanilla or peppermint, or will it interfere with the surface tension?
-Can you figure out how to make a bubble inside another bubble?
I can’t get over how young my kids look in this post, which I first published a few years ago. This is a great science/art crossover project and one of these bracelets would make a fantastic Mother’s Day gift! Just bring an extra bag along and pick up some extra flowers, petals, leaves and seeds for mom’s bracelet. You can assemble it when you get home. Just leave one edge leaf-free so you can put it on her wrist!
Spring has finally arrived, and a fantastic way to enjoy it is to take a nature walk. While you walk, watch for signs of spring and assemble your discoveries on your wrist with a nature walk bracelet. It’s always a good idea to bring a few bags along too- one for larger treasures (like pine cones) and one for trash. You can study nature and clean up the environment at the same time!
All you need is duct tape. Cut the tape so it fits comfortably around your wrist and tape it around like a bracelet, sticky side out. Take a walk in a park or down your own street and look for small leaves, acorns, flowers and other natural artifacts to adorn your wristlets. Be sure to watch for birds while you walk! There are a number of great apps you can use to identify what species of plants you find, including Leafsnap!
We wore our bracelets all afternoon and several people mistook them for real jewelry. My oldest daughter thought they looked even prettier as the leaves and flowers wilted and flattened out on the tape.
Every fossil has a story to tell.
Whether it’s the spectacular specimen of a dinosaur curled up on it’s eggs or a tiny Crinoid ring, mineralized remains offer us a snapshot of the past, telling us not only what creatures lived where, but about how they lived and the world they inhabited.
Growing up surrounded by the flat-topped, windswept Flint Hills of Kansas, it was hard to imagine that I was living in the bottom of an ancient seabed, but there was evidence of the Permian period all around.
Now, when my kids and I return to my hometown, a fossil-hunting trip is always part of our routine, and we hunt for shells and coral where roads cut through crumbling limestone and and chert (flint.) Looking up at layer after layer of rock and shells, I can almost feel the weight of the water that once covered the land.
An episode of RadioLab we heard on the drive North from Kansas to Minnesota explained that coral keeps time and that by comparing modern coral to ancient coral fossils, scientists discovered that millions of years ago, years were about 40 days shorter than they are now. Can you guess why? Give the podcast a listen here. My mind was blown!
A visit to the Flint Hills Discovery Center in Manhattan, KS gave us more insight into the amazing geology, ecology and anthropology of the Flint Hills and the Konza Prairie that blankets them. Most people don’t know that the great tallgrass prairies of the United States wouldn’t exist if not for humans, who have been burning them for thousands of years.
What do you know about where you live? What’s it like now? What do you think it was like long, long ago? Are there fossils nearby?
Here are some fossil-hunting resources I found online, in case you want to go exploring:
When I do science outreach with kids, I encourage them to get creative and try different ratios of ingredients in experiments like Mad Scientist’s Green Slime, to see how their results will vary. Will they get stretchy goo, or bouncy balls?
This morning, I decided to explore the kid in me and see what fun new experiment I could come up with, using the ingredients for polymer slime. After lots of giant failures, I came up with a fun way to combine two experiments: Mad Scientist’s Green Slime and Paper Bag Volcano. My kids gave it a big thumbs up and gave the experiment a fun name. Hope you like it too!
For this experiment, you’ll need: Borax laundry detergent (powder), baking soda, glue, vinegar and a full small 8oz plastic water bottle.
1. Remove the label from the bottle, take the lid off and pour out about 2oz of water.
2. Add 1 tsp. Borax and 5 tsp. baking soda to the water in the bottle (we used a paper funnel.) Put lid back on and shake well. Label bottle Borax/Baking soda.
3. Mix together 2 Tbs. vinegar, 2 generous Tbs. glue and a few drops of food coloring. Mix well and transfer to a pouring container, like a paper cup with one side pinched into a spout.
4. Shake the bottle of Borax/Baking soda solution up again and set it in a large bowl. Remove the lid from the bottle.
5. Pour the glue/vinegar solution into the water bottle very quickly, all at once.
6. When your bottle has stopped “erupting,” squeeze the foamy slime out of the bottle into the bowl and mush it all together.
7. Enjoy your foaming slime monster! What would happen if you added glitter? Does the amount of glue you added make a difference? What if you added more?
The science behind the fun: Polymers are long chains of molecules, like a long string of beads on a necklace. In fact, polymer means “many pieces!” Glue contains a chemical called polyvinyl acetate, a polymer that is runny when you mix it with water or vinegar. However, if you add Borax detergent, a crosslinker, it makes all of the glue molecules stick (or link) together in a big glob.
When you mix together baking soda (sodium bicarbonate) and vinegar (acetic acid), you’re doing a chemical reaction. One of the products of this reaction is carbon dioxide gas.
In this experiment, when we pour the glue/vinegar into the baking soda/Borax solution, we mix baking soda and vinegar at the same time as we link glue molecules together, trapping gas bubbles inside our gluey polymer slime. Your “slime monster” escapes as the slimy bubbles push their way out of the bottle under increasing pressure.
Feel free to share this experiments with your friends. If you’re sharing it on a website, please link back to this post though, since it’s an original experiment!
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!
This morning my 9 YO came down the stairs and told me she does the soap science experiment every time she washes her hands.
“Which one?” I asked.
“The one where the soap jumps!” she said, demonstrating for me by pouring a thin stream of liquid hand soap from one palm to the the other. “Sometimes it jumps clear out of the sink!”
Over a year ago, my daughter and some of her friends helped me do this “Kaye Effect” experiment (shared with me by Dr. Greg Gbur) for my book “Kitchen Science Lab for Kids,” but I had no idea that it stuck in her mind, or that she’d figure out a new way to do the experiment.
Maybe some day in the future, she’ll remember that shear-thinning fluids like soap can “jump” and it will help her solve a problem, or even create something new!
Here’s my original post on the Kaye Effect.