A simple machine is a mechanical device that changes the direction or magnitude of a force. A pulley is a simple machine made from a wheel and cord, used to re-direct force. Some pulley systems make work easier, allowing the use of less force to move an object.
The pulley's cord moves through the pulley to change the direction of a pulling force (e.g. lift heavy objects UP by pulling DOWN, move objects LEFT by pulling RIGHT).
These activities are part of Science World's Big Science for Little Hands program Gadgets and Contraptions. They were developed and tested with Preschool and Kindergarten educators.