Halloween should be a special day in the science classroom. Above, is a photograph of a “class pet” that I once had. Although it was just an enormous sweet potato, the kids got a kick out of the set-up.
Making carbonated ice cream is a significantly bigger commitment. The “recipe” is simple – simply add a block of dry ice to any ice cream/smoothie/chocolate milk type mixture that you please. The dry ice will whiz around spectacularly, especially if the block is not too heavy, create tons of cold fog, and make science fiction-y noises if you use a metal mixing bowl. The challenge is bringing dry ice into the classroom. There isn’t any simply way to make that happen, but if you can pull off the logistics, it is well worth it. I once bumped into a student with whom I’d made carbonated ice cream with 10 years earlier, and she told me that the activity convinced her that maybe science was worth paying attention to after all. There is a lot of science to talk about with carbonated ice cream, too. The precise angle I take depends on the class, but I’ve most often used it to illustrate the solubility of a gas in a liquid. (One safety note – if you’re doing anything with dry ice, it is important to make sure you have good ventilation.)
I don’t post recognizable photos of my students online, so the photo below is of myself and two adult friends making carbonated ice cream at a picnic.