The reading introduces the children to a simple machine in the form of the pulley. It may be used as part of a class discussion or as a paired reading, followed by discussion. Samples of different types of pulleys would enhance the lesson tremendously.
• The children will understand how a basic pulley works.
The children will be able to carry out simple calculations to measure the mechanical advantage of different pulleys.
The pulley is simply a wheel, which has a groove around the outside edge. A rope or belt fits into the groove and is connected to the weight you want to lift. When effort is applied to one end of the rope ? in other words, when you pull on the rope ? the load, which is the weighted object on the other end, is lifted off the ground. It is easier to lift by pulling down on the rope because then gravity is on your side. The first diagram shows a simple pulley which is attached to a beam. This is a fixed pulley. In the second diagram, there are examples of moveable pulleys.