The art teacher at my school used the meat trays for giving out paint to students in small amounts and providing a spot to mix colors. The thin flat magnets that accumulate over time can also be used in an art class.
I taught Home Economics and used coolwhip type and other plastic containers in class instead of buying storage containers-recycling in use. We also made tin can ice cream with 1 lb and 3 lb coffee cans. the ingredients went inside the small can, inside the large can, filled the area between wtih ice and salt, and rolled the cans until we had ice cream. Kids loved it. Easy to repeat at home.