This set of 3 wooden friction blocks features three different surface materials for comparative friction studies: bare pine wood, sandpaper, and felt. Each block measures 6 x 3 x 1.25 inches and is fitted with a c-hook at each end for attachment to a spring scale. Students attach a spring scale to the hook and pull the block along a flat surface or up an incline, reading the force required to overcome friction. By testing each surface and varying the normal force (adding weights on top), students can calculate and compare coefficients of friction. A hands-on tool for teaching friction, kinetic and potential energy, acceleration, and force concepts to students of any age. Manufactured in the United States.