Friction blocks are useful for teaching the basics of force and motion in a simple, yet effective way. Fitted with a c-hook, the block can be attached to a spring scale to measure incident forces. Slide the block along a flat surface, or pull it up an incline. Observe the block by itself, or add weights to the top. Measure differences in coefficient of friction between the felt, sandpaper and pine surfaces. A friction block used in tandem with a spring scale is a powerful tool for teaching students about friction, kinetic and potential energy, acceleration, and force. Each block measures 6 x 3 x 1.25" and is sourced and manufactured in the United States.