Task 8

Materials and tools for a working group:

dynamometer, material for pulleys construction (wheel, plate, string, nail, paper clip – or what the pupils suggest), bucket with load

In the following task, pupils compare the use of fixed and free pulleys. The teacher can start discussing whether pupils have ever seen a pulley. It is important to show the pulley that the pupils know what the teacher is talking about. They could see the pulley, but they might not be able to name it. The task of pupils is to find as many devices as possible on the Internet that use the pulley. In this way, pupils realize that pulleys are used in many places, and are usually designed to simplify the hauling of loads. The teacher suggests that the pupils try to create the pulley and check its functionality.

First, they construct the pulleys according to the drawing scheme (worksheets). The teacher guides the pupils to describe how the fixed and free pulley isdifferently constructed. The teacher will draw pupils‘ attention to details. The teacher leads the pupils to make predictions linked to the new research question: Is there a difference in the amount of effort exerted when pulling the load using a fixed and free pulley? This time they formulate predictions in their own words. Consequently, they verify the predictions by constructing and comparing the pulleys with the use of a dynamometer. Theyformulate the result of the observation in the form of an answer to the research question. Pupils find that the use of a free pulley reduces the effort that is required to pull the load up to half compared to a fixed pulley. They also find that by using a fixed pulley we put as much force on the load as without using it.