My girl showed me an awesome trick today: by twisting a nearly-empty water bottle at its middle, you can make the water inside it boil. Watch out for that lid when it pops, not to mention the escaping steam! We recommend trying this outside, and wearing the wrapper like an upcycled wristband. ;)
Two other neat tricks to try:
Take an empty plastic water bottle through airport security before your next flight. They will make you throw it away if there’s any liquid in it, but once you’re through security you can fill it up again. When you’ve finished the water, and while still at cruising altitude, and take off the lid to allow some lower-pressure air inside. Screw the lid back on tightly. The bottle will compress or even collapse as you land into what should be a higher air pressure area. “Mama’s Little Book of Tricks” suggests telling your kids you will crush it with your mind. While they observe the bottle, you’ll observe how quiet they are. You can explain the science later. :)
And here’s one I wrote about on my old blog: how to make a cloud in a bottle. In short, put the lid on a just-emptied water bottle, and set it in a sunny window where the water inside will evaporate. When that’s done, add a bit of smoke from a just-blown out match, then put the lid back on again. Then give it a squeeze and let go. The air pressure inside the bottle will drop and a tiny cloud will form. Or, you may already have a cloud, which will disappear when you apply pressure to the bottle. Give it a try and tell me what you think!