In this kit, students discover and apply the concepts of density and buoyancy by creating a sugar or salt gradient in a plastic column and floating five small spheres in the solution. Each sphere floats at a different level! Includes full instructions and write-ups as well as spheres made of polyethylene, polystyrene, nylon, acrylic, and cellulose acetate. Unknown plastics are also included for student density determination. Great for an elementary science table or as a terrific lab for middle school, high school or college.