CME Gators 2006 / 2007 Density is a measure of how tightly the particles of a substance are packed.  Denser substances will sink in less dense substances. The “Magical Rising Egg” is an exploration of the concept of density. Here’s another density investigation.  Saltwater is denser than fresh water. Freshwater should, therefore, “float” on top of saltwater. This student is a superstar.  M.C., wherever you are, I wish you well.