As a kid, I was always fascinated by stories of pieces of straw from a field being driven into wooden planks in barns and houses by the swirling winds.
With a potato, plastic drinking straws and a glass of water, you can see for yourself how this happens. Like drinking straws, real straw is hollow and although a potato is much softer than a piece of wood, you’ll get the picture.
You’ll need a potato and some sturdy plastic drinking straws.
Begin by soaking a potato in a glass of water for about 30 minutes to soften the skin. We used a red, boiling potato, because that’s what I had on hand.
Then, grasp a straw tightly, near the middle and stab it into the potato as hard as you can. Try starting at different distances from the potato to see whether it makes a difference in how far the straw goes in. (You can mark it with a Sharpie and pull it out.)
We were surprised to find that, instead of breaking or bending, the straw can be driven surprisingly deep into a potato . This happens because objects in motion, like the straw, tend to stay in motion and objects at rest, like the potato, tend to stay at rest. (Newton’s First Law of Motion) This is called inertia. In addition, the paper-thin edges of a drinking straw don’t offer much resistance, and potatoes are composed of around 90% water.
You’ll need 8 oz water bottles, glue, Borax detergent, baking soda and vinegar.
First, decorate full 8 oz water bottles with tape, marbles and whatever else you can find.
Then, follow these directions to make foaming slime ooze out of their heads, using a simple chemical reaction! You’ll love it!
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 talked summer science with Ira Flatow and Lynn Brunelle on Science Friday (NPR)! We swapped ideas for water rockets, pitfall traps and leaf paint, among other fun things. You can visit Science Friday’s website and listen by clicking here!
Click here for more details!
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!
sar·coph·a·gus (särˈkäfəɡəs/) noun-
a stone coffin, typically adorned with a sculpture or inscription and associated with the ancient civilizations of Egypt, Rome, and Greece
Two weeks ago, we mummified some apples, a hot dog and a game hen (see previous post). Today, we dug the mummies out (see video above) and found that they’re drying out nicely! I thought it would be fun to add some science art to the project! After all, pigments are molecules that give things color and paint is made from pigments like Zinc Oxide (white), Black Iron Oxide, and Silicate of Sodium and Aluminum with Sulfur (blue.)
The ancient Egyptians were amazing artists, and historians think they made paint using materials and pigments they had on hand, including eggs, casein glue made from milk, wax and gum from local trees. This paint was used to decorate everything from tombs to coffins.
We covered one of our plastic ware “coffins” with masking tape, used plaster of Paris to make it more stone-like and made casein glue from milk and vinegar using this glue recipe (casein science on this link). To the glue, we added pigment until we achieved the desired color, and then stirred in a little bit of water to get the paint-like texture we wanted. We bought the pigment at Blick art store, but didn’t buy red or yellow pigment, since they were pretty toxic. The brownish-yellow is made from Curry spices. I’d like to try the spice turmeric for a more pure yellow!
Can wait to see how our sarcophagus turns out! I’ll post a photo when we finish painting it!
When mixing up materials to make a mummy, don’t forget the salt!
Natron, which was used in Ancient Egypt to preserve mummies, is a natural salt mixture containing sodium carbonate decahydrate (soda ash), sodium bicarbonate (baking soda), sodium chloride (table salt), and another salt called sodium sulfate. Salt is a dessicant, which is a chemical that removes water from things. It also has anti-microbial properties, which means it kills bacteria and fungi. When you remove water and microbes from the picture, mummies bodies’ don’t decompose.
Today on WCOO, we mummified some apples, hot dogs and even a game hen, which is like a small chicken. Here’s an old post on how to mummify apples.
First, we’ll weigh everything we’re going to mummify, so we can see how much water weight they lose during the dehydration process.
We’ll rinse and blot the game hen with alcohol to kill some of the microbes on the outside, add aromatic spices like cinnamon and cloves, and put it in a container filled with a 50-50 mix of baking soda and salt (Kosher salt or table salt will work), where we’ll let it sit for about 40 days, changing the salts once or twice over that time period.
Real mummies are coming to the Science Museum of Minnesota! Mummies: New Secrets of the Tombs opens at the Science Museum of Minnesota on February 19. The exhibition, which features mummies from the preeminent collection of the world-renowned Field Museum in Chicago, juxtaposes ancient specimens with the modern science that has given us new glimpses into ancient Egyptian and Peruvian cultures.
Today on WCCO MidMorning, I’ll be talking microbiology! According to the CDC, hand washing is the best way to remove microbes from your hands.
You can see what bacteria and fungi are hanging out on your fingertips by touching homemade petri plates to grow colonies. Test your fingers before and after washing with water alone, soap and water, and finally hand sanitizer. You can find the experiment in my book, Kitchen Science Lab for Kids, and here on my website. The video below shows you how to make plates.
It’s simple to stir up some Halloween magic with a head of red cabbage and some baking soda and vinegar.
Chop us half a head of red cabbage (with adult supervision, of course), put it in a sauce pan, cover it with water and boil for 10 minutes or so, until the water turns purple. Let it cool, strain out the cabbage and save the purple juice, which is your Magic Potion.
Pour about half a cup of the purple juice into each of two clear cups or bowls.
To one cups, add 2 tsp. baking soda and stir. What happens?
To the other cup, add 1/4 cup vinegar. Amazing!
Now, put the two cups on a tray or cookie sheet and pour the pink cup into the blue cup quickly. Woo Hoo!
Here’s a video, if you want to see how the experiment works.
Everything in our world is made of very tiny pieces called atoms. When atoms bond to other atoms, they form groups of linked atoms called molecules.
Purple cabbage juice is called an acid-base indicator. The molecules in the cabbage juice magic potion change when exposed to an acid or base, making the potion change color. Vinegar is an acid (acetic acid), which turns the potion pink and baking soda (sodium bicarbonate) is a base, which turns it blue or green.
When you mix the vinegar potion and baking soda potion together, a chemical reaction occurs and you make Carbon Dioxide gas. That’s why you see bubbles!
Soak coffee filters in leftover cabbage juice (if you have any) to make Homemade Litmus Paper!
Have fun experimenting! Happy Halloween!
At home science offers an opportunity for kids to have fun and be creative thinkers. This holiday season, help your kids take a break from screens with an activity they’ll love, like blowing up balloons with baking soda and vinegar!
Wrap up Kitchen Science Lab for Kids (available wherever books are sold) with a box of baking soda, a bottle of vinegar and some balloons for an instant holiday hit.
Better yet, put together a homemade science kit for the kids on your list and let them choose and experiment a day to do over break. (Many of them are easier than baking cookies.)
Put kids in charge of the experiments. Let them try whatever they want, as long as it’s safe, even if you don’t think it will work. We learn to be creative when we’re given freedom to make mistakes and go beyond the instructions.