In this lab student teams need to take both mass and volume measurements for various objects and compare them. This lab is leading to the idea that mass and volume do not increase or decrease in regular increments and that these two properties of matter combine determine an objects density. It provides additional volume practice as well. Following the lab are analysis questions that guide students to think about the measurements they took and leads them to discovering density without yet defining it as that.
You will need scales that measure mass to 1/10 to 1/2 gram as scales that measure only in whole grams do not provide enough accuracy,
The film canisters should have one empty and the other 2 filled with different amounts of salt, sugar, or some other dry substance that will not leak. The old black film canisters are what I use with lids so the kids don't know wha's inside. I label the lids with masking tape and their number.