Summer break is coming. Which means it’s time to bring the classroom home, and keep young minds active for the next few months. Here are a few quick scientific activities to spark curiosity and discussion at home.
Cloud in a Jar
For this activity, you need a big glass jar with a metal lid that seals tightly, a cup of very hot water, a match, and a bowl of ice cubes.
The adult in the room should pour the very hot water into the jar, and then light the match and drop it into the jar, immediately clapping the lid on and screwing it tight. Then, pile as much ice as will stay on top of the lid. Don’t move the jar at all, just look into it. A cloud should form!
This happens because the heat from the boiling water has put a lot of moisture into the air as evaporation, and when that moist air encounters the ice-cooled lid, it condenses again. The tiny trace of smoke from the match helps this condensation, giving the particles of water a place to start.
For this activity, you need a cup of very salty water in a large bowl (either from the ocean or mix two tablespoons of salt into a cup of hot water), a small, empty bowl, a sheet of plastic wrap, a marble, and an undisturbed spot that will be in direct sunlight most of the day.
Put the small bowl inside the big one, right in the center. Make sure that the salt water doesn’t get inside it. Next, stretch the plastic wrap over the top of the large bowl, so it seals around the edges. Put the marble in the middle of the wrap so it dents it down, making a low spot. Leave it all sitting in the sun, and come back after a few days. If it’s very hot and sunny, maybe only a few hours! Eventually, all of the salt water should evaporate from the big bowl, condense on the plastic wrap, and drip down into the small bowl, but now as fresh water.
This happens because when salt water evaporates, the actual salt will be left behind (you’ll find it crusted in the big bowl. If it’s sea water, maybe don’t let your kids taste it). So only fresh water gathers on the plastic and runs down to the low spot created by the marble’s weight to drip, drop by drop, into the small bowl.