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.
If I give you glue, water and Borax, can you come up with a recipe for perfect polymer slime based solely on what you know about the science?
Last week, I did hands-on science with 150 third graders at Success Beyond the Classroom’s Creativity Festival at the University of Minnesota. As they came into the room, I asked them to draw a picture on chalkboard of anything related to science. They drew test tubes, trees, volcanoes, and even scientists!
Then we dug into the science. After doing my favorite large group hands-on experiment with purple cabbage juice to warm them up, I announced that we’d be making polymer slime, but that they would have to invent the recipe for the perfect goo.
To begin with, I talked about the science. We learned that one ingredient in the slime is glue (polyvinyl acetate), which is a polymer, or long chain of molecules. Then, we talked about the fact that adding water to the glue makes it less viscous, or thick. As usual, I had them repeat the vocabulary after me. Finally, I explained that the sodium tetraborate in Borax laundry detergent is a cross-linking substance that makes glue molecules stick together, and that we’d mixed up some Borax and water for them to use as a crosslinker for the slime.
Their challenge was to come up with one “recipe” to make a gooey, soft slime and a second recipe for a harder, rubber-like slime that could be rolled into bouncy balls. They each had a note card and pencil to keep track of their work, plastic teaspoons as measuring tools and paper cups for mixing slime. First, they’d stir up different proportions of glue and water, and then they’d add the Borax solution as a cross linker and mix it all together with a popsicle stick. To make it a little more colorful, they could add a drop of food coloring or some cabbage juice.
Needless to say, there were failures and successes and the kids had a blast. We talked about the fact that experiments often don’t work on the first try, and each kid explained to the group how they’d made their perfect slime as they demonstrated how it bounced and stretched.
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 use alum crystals to make ordinary objects extraordinary with science!
We coated pipe-cleaner snowflakes, styrofoam snow people and even an evergreen branch with gorgeous ice-like alum crystals. We demonstrated how to make these on Kare11 Sunrise News.
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! See below.) 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.”
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, causing the other atoms to come out of the solution and attach to the seed.
What else can you think of to crystallize?
In addition to some of my neighborhood friends,two awesome chemist friends helped me out with this song: the amazing Dr. Raychelle Burks (with the Bronsted-Lowry line) and bassist Ryan Williams, who happens to have a PhD in Chemistry, with his awesome bass-playing.
The video quality isn’t top-notch, but you’ll get the idea, and hopefully learn a little chemistry!