Probably have to go through how to find volume of a foil boat. Also may have to discuss what goes into good graph. If time permits, also have students find mass for given volume of water. Introduce concept of density. Add in how concept is so difficult because it involves two variables at once.
Salt water is denser than fresh water.
Ask Q's about which floats on top, and whether boats floating in one will float in the other. Article or Consumer Product testing due Wednesday.