This is an introductory lab to test the student's observation skills. Simply fill 10-20 old black/gray film canisters with "mystery objects" rice, erasers, staples, rubber bands, etc. Instruct students that they must determine what is in the canister but CANNOT remove the lid. I provide my students with choices.
Once every group is done, I go through each canister. The students have fun seeing what is actually in the canister. :)
For extra credit I make one that contains a cotton ball. The kids really get a kick out of that one!