Why does wood float and iron sink? The answer has to do with density, an often difficult concept for youngsters to comprehend. Density cubes clarify the topic by providing a tangible, hands-on way of learning about mass, volume, specific gravity, buoyancy, and flotation. The set contains 10 one-inch cubes, each made of a different metal, wood, or type of plastic. Each cube has a unique density and weight. When the cubes are used in classroom activities, students can actually see, feel, and touch the concept. Includes instructions for use in the classroom.