This wooden pendulum has a strong and sturdy construction ideal for classroom use. It helps teach that pendulums consist of a body fixed at a point; when the body is displaced from that point it oscillates back and forth under the force of gravity.The blue pendulum bob is adjustable so that students can easily and quantitatively study the relationship between the length of the pendulum and the period of the bob. The wooden guide helps students keep the release angle uniform and small. The rigid body allows for movement in only two dimensions keeping students focused on the relationship of length and period without having to worry about other variables.Includes an instruction manual to facilitate student and teacher use of the apparatus.39cm tall with the wooden pendulum32cm wooden pendulum with adjustable bob.Base is 9cm x 16.5cm