A pulley is a variation of the wheel and axle, in which a rope or cord is stretched over a wheel to make it rotate as the rope is pulled. Help students understand the advantages of pulleys using this model from Eisco®. A teacher's manual containing student experiment worksheets is included. A 5-N spring scale/dynamometer (item #751957), masses (item #751448), and extra string (approximately 4 ft) are needed to complete the experiments but are not included.