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.
My 9 YO and I did some fun experimenting yesterday to figure out the best way to make bath bombs. As a starting point, we tried a few recipes off of the internet. The first was was crumbly and smelled too strongly of olive oil, and the next one was equally tricky to work with. After our first two failures, we looked at our results and decided to omit the water in the recipes, using just coconut oil to hold the mix together. It worked well! Here’s the recipe we came up with. You may have to tweak it a little by adding a tiny bit more oil to make the perfect bath bomb mixture!
1 cup baking soda
¼ cup cream of tartar
2 Tbs. coconut oil, melted to liquid
empty contact lens case
-Whisk together baking soda and cream of tartar. Slowly drizzle in coconut oil, mixing immediately. Stir for several minutes until you get a nice even mixture that holds together when you press it between your fingers.
-Separate the mix into 3 or 4 bowls, and add a few drops of food coloring to each bowl. Mix again until color is incorporated.
-Press the bath bomb mixture into empty contact lens cases and gently tap the backs with a spoon to remove fizz tablets. It may take a few tries to get the hang of it! If they don’t stick together, try adding a little more oil and mixing again. Dry the bath fizzies on a plate or cooking sheet and package in cellophane bags or pretty baking cups for friends and family. Use your fizz bombs within a few weeks for maximum fizziness!
–Older kids can make larger “bath bombs” using molds for round ice cubes (which we found at Target.) Double or triple the recipes, gently press some mixture into each side of the mold, and mound a little extra on each side. Press the mold together to compress the bath bomb mixture into a single ball. Tap one side gently with the back of a spoon and gently open the mold to release that side of the sphere. Hold it in your palm and repeat with the other side to release the entire bath bomb from the mold.
The science behind the fun: The chemical name for baking soda is sodium bicarbonate, and cream of tartar is potassium bitartrate, or potassium hydrogen tartrate. When you mix them together in water, you create a chemical reaction that forms carbon dioxide gas bubbles! It’s interesting to note that at temperatures below 76 degrees F (25 C), coconut oil is a solid, but that at temperatures above this, it melts into a clear liquid. How does this affect your bath fizzies? Will they work in cold water as well as they do in warm water? Try it!
Here are some great last-minute experiments to make your Halloween more fun and spooky! Watch the TV segment I did to see how much fun they are, and look for links to directions below the video.
Click on these links for instructions on how to make Frankenworms, Cornstarch Goo, Mad Scientist’s Green Slime, Alien Monster Eggs, Magic Potion and Bags of Blood. You can find more experiments by scrolling down on my website!
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!
Here’s how to make them!
Find written directions by clicking here.
I’ve been having fun with fermentation the last few weeks and my kids loved making root beer. In a week or two, I’ll post instructions, but here’s a general how-to demo I did on WCCO MidMorning.
My posts have been spotty this summer, since I’ve been busy working on a follow up to Kitchen Science Lab for Kids. Yesterday we supercooled water to see what would happen. It was tricky to get the temperature just right, but when we did, this is what happened!
To supercool water, chill purified water in your freezer, or in a cooler with salt water and ice. Chill an equal volume of tap water in the same cooler. Keep an eye on it. When the tap water is completely frozen, but the purified water isn’t, the purified water should be supercooled. Carefully remove it from the cooler, gently remove the lid and slowly pour it over an ice cube to duplicate the experiment above. If you drop it or jar it, it will probably freeze and you won’t be able to use it.
Without a trigger for crystal formation, motionless water molecules can remain in a liquid state below the normal freezing temperature of water. In this experiment, tap water freezes first since ice crystals often form on impurities in the water. Other ice crystals quickly form around the seed crystals, eventually freezing the entire bottle into solid ice.
In supercooled purified water, a crystal lattice of ice can also begin to form at the result of motion, or impact. Once crystal formation begins at a single spot, all of the other supercooled water molecules snap into formation, forming solid ice.
Try it! It may take more than one attempt for a great result, so freeze several bottles at a time.
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!