Six hardwood simple machines exploring different properties of physical science. The Fulcrum Balance allows children to move the weights on either side of the fulcrum to create balance, the Pendulum shows mass in different positions on the pendulum as it relates to timing and swing, the Inclined Plane allows changing force by changing the angle, the Wheel & Axle can operate several ways similar to a crane, the Gear moves back and forth with teeth connections, and the Pulley can move weight with its system of wheels and cord. The Gear is 15" L. The Pulley is 15½" H. Includes Teacher Guide. Set of 6. Ages 4 yrs. +.