Elephant ToothpasteThis is one of my absolute favorite projects we do regularly at the science museum. I highly recommend it for kids and adults of any age at all. There's a lot of tactile value and observational practice inherent to the activity, and it can be hugely entertaining for a long long time. Just make sure that if you do this with really little kids, they shouldn't eat or put any of this stuff in their mouths, and you should probably handle the hydrogen peroxide for them.
Things you'll needMix activated yeast and warm water inside the empty water bottle. Allow it to sit for 5 - 10 minutes (not always necessary, but it seems to get the best reaction). After yeast has activated and is all foamy, put 1 - 2 quick squirts of dish soap directly into the mixture in the bottle. Next, add whatever food coloring you like. If you angle the bottle so that the food coloring runs down the inside of the bottle, you can get the stripy effect that makes this look like toothpaste. Ok, here's the fun part: have the bottle in whatever location you are prepared to have a soapy mess. When you're ready, pour in 1/2 cup of hydrogen peroxide into the bottle, then watch closely! The mixture will start to foam, fast! Eventually, it will probably reach the top of the bottle and start oozing out and getting everywhere. You can touch it, play with it, smell it (don't eat it), just have fun!
- empty and cleaned plastic water bottle or similar container (make sure the label is removed so you can see the reaction inside)
- 1 tsp. dry activated yeast
- 2 tblsp. warm water
- squirt of dish soap
- food coloring of your choice
- 1/2 cup hydrogen peroxide
- lots and lots of paper towels, or a location you don't mind getting... erm... soapy
What's going on here?The term elephant toothpaste is a really weird misnomer, because it has nothing to do with elephants, and it certainly isn't toothpaste. It is a really really cool chemical reaction between the yeast and the hydrogen peroxide, and it can smell like soapy bread (which I think is strangely nice). When you pour the hydrogen peroxide into the activated yeast, the yeast begins breaking down the molecular bonds of the hydrogen peroxide. Hydrogen peroxide is made of two hydrogen molecules and one oxygen molecule: H2O2. When it gets broken down, the molecules recombine into two new compounds: H2O (liquid water) and O2 (dioxygen, which is the common form of oxygen gas). All that new water and oxygen go nuts in the bottle and they get together with the dish soap you squirted in there. The water, oxygen, and soap create thousands (maybe millions?) of soap bubbles in the bottle and erupt out the top. So, after the reaction, you have a good-sized puddle of soapy water, and maybe some yeast bits left in the bottle. If you feel the soap, you might notice it is a little warm. That is because the division and recombination of the molecules takes some energy, and that energy comes off as heat. Neat, right? You can reuse the bottle several times with this experiment.
Extract your own DNAWhen I first saw this on a blog feed somewhere, I literally jumped out of my seat and immediately started gathering the materials to do it. Remember, I am a single adult woman with no children of my own, and I only ever interact with kids at work or the occasional family get together. This particular time I was sans kids, and I was still completely captivated by the project. I mean, I got my own DNA in a cup!! The project comes from PBS Nova, here's their video, and following it is the step-by-step in text. Side note: if you do this with a group of people, make sure everyone uses their own gargling cup... sharing ≠ caring, in this case :/
Things you'll need:Combine water and salt in one cup. Stir until dissolved. Transfer 3 tablespoons of the salt water into one of the other clear cups. Gargle this water for one minute then spit the water back into the same cup (ew!). Dip one end of the stir stick into the dish soap. Then, very gently stir the gargled spit salt water with the soapy end of the stick. Stir slowly so that you won't make bubbles. In the last cup, mix together the alcohol and three drops of food coloring. Now, tilt the spitty soapy salt water cup while gently pouring the colored alcohol into it. Doing this slowly and with a tilt will keep the alcohol from mixing too much with the salt water, and should form a layer of alcohol on top of the water. Wait a couple of minutes until you see some clumps and strings forming. Those bits are... YOU!
- 2 cups or 500 mL drinking water
- 1 tblsp table salt
- dish soap
- food coloring (dark colors like blue work best)
- 1/2 cup or 100 mL 70% Isopropyl alcohol (common rubbing alcohol)
- clean stir stick, like a skewer or coffee stirrer
- 3 (large) clear cups
What's going on here?The video includes a lot of the "what's happening" in it, so just to recap: when you gargle the salt water, you collect cheek cells in it. The soap you mix in breaks the membranes of those cheek cells and releases the DNA into the water. The colored alcohol is a solution that isolates the DNA from everything else and you can see it in contrast to the color. I just think this is downright amazing. It was just less than 150 years ago Friedrich Miescher first isolated DNA, and then since him, a series of intense research and experimentation to figure out what the heck it was; including Watson, Crick, and Rosalind Franklin who worked on figuring out the structure of DNA less than 60 years ago. And I can do this in my kitchen, out of an enthusiastic whim, in less than 10 minutes!
Water GooIn the debunking post, I mentioned the water marbles hoax that claim you can mix a bunch of ingredients together to make marbles out of water. Even though that was not real, there are some cool at-home experiments you can do that are related to hydrophilic materials like the toy used in the hoax. This also gives me a chance to talk about diapers, particularly the ones I used to change on my sister. She's 12 years younger than me, a gorgeous 14 year-old, and she's about to start high school. But once upon a time, I was a kid myself, and she was a little baby who wasn't potty trained. For some reason, potty-training Malia is one of my favorite memories about her childhood. I was typically responsible for diaper duty, and I never grumbled about it or anything because, well, babies need this service and I liked her a lot. But I was confounded by some things related to diapers: 1) why didn't the *** leak out the diaper, and 2) what are these little jelly things on this baby's butt? When I got older and started working in daycares, I noticed the same thing on the babies there (maybe you've had a similar experience). Now that I am even more older and I work in a science museum, I have found my answer... (partially adapted from Cool Science)
Things you'll need:Cut open the diaper by cutting along the sides so that you can get to the soft material sandwiched inside. Pull this soft material apart and you'll start to get some white powder from it. Collect the powder in a cup or a dish and continue mining the diaper. When you've got as much as you can, put all the powder into a small bowl. Add water, about a tablespoon at a time, and watch what happens!
- A clean UNUSED baby diaper (also, don't try to use it after doing this experiment)
- Sharp scissors or an exacto knife
- A cup of water (tap is fine)