Pass 35 mm film canisters with different masses inside to students and have them place in proper order from lightest to heaviest
Case 8: Beans, Case 6: Sand, Case 10: BBs, Center Case: Lead
Another Version:
A set of plastic bottles with lids. One is faintly pink, another faintly yellow, a third mostly transparent, and the fourth dark grey. The contents of each are a mystery, with the exception of the mostly transparent container, which seems to be full of small spheres, largely silvery in color.
