The colorful set consists of 48 specimens of twelve different types of material. The specimens are packaged in an acrylic tube as 12 sets of four. Set includes samples of Maple wood, Polypropylene, Nylon, Acrylic, Polyurethane, Phenolic, PVC, Copper, Brass, Teflon, Polyethylene and Aluminum. Students measure the mass and volume of different specimens and graph their masses as a function of volume. The graph produces a line for each substance, whose slope equals the density of the substance. Students learn that the density of a substance is constant even as its mass and volume change. With instructions.