Young students are familiar with the observable effects of force and motion but may not have considered the many varieties demonstrated in simple ways every day on the playground. A force is simply a push or a pull. A force can make an object move, move more quickly, change direction, slow down, or stop. Forces cannot be seen but their effect can be felt. When the push or pull results in movement, motion is observed. To make an object move, a force must be exerted on the object. At recess, a simple game of catch is started using muscular force. If the ball isn't caught it will not stay in the air forever. Gravity is the force that causes the ball to slow down and fall to the ground. The various types of motion are visible all around us: a bicycle, a yo-yo, a slinky, and an amusement park ride are some fun examples. Motion can be simple or complex: The key is to provide children with the skills to describe, predict, and apply motion knowledge to help them understand the world around them.