This lab is an inquiry activity if it is done before the discussion of how center of mass and balance are related. However, students should have an idea of what center of mass is before they start the lab. Students should see that when the center of mass is high (the can is full), the can will tip over. The more fluid in the can, the farther to the right the center of mass will go on the diagram. When the water level gets lower, it centers itself in the V-shape of the bottom of the tilted can and the center of mass remains above the base over quite a range.