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MODULE 4 THE POWER OF FORCES LESSON 6: HOW STRONG ARE THE MAGNETS? LESSON SUMMARY: In this lesson children will build on their work in Lesson 5 and will test different magnets to compare their strength in order to test a number of given statements. By the end of the lesson children will have learnt that the largest magnets are not always the strongest and they will be able to use the results of their investigation to support or refute statements. EXPLORE: Display Slideshow 1. Ask the children to discuss each of the statements and then to decide which child they agree with. Use a show of hands to see who agrees with each child. Show the children the video of the activities from Lesson 4 (Lesson 4, Video 1). Remind children of how they tested a magnet in various ways, such as how many paperclips in a chain could a magnet hold, or what was the heaviest object the magnet could pick up and how much did that object weight. Explain that they will choose one of these methods to test the strength of a range of magnets in order to give evidence to support or refute the statements discussed. ENQUIRE: Arrange the children into groups, and give each group six magnets of differing size and strength labelled A–F. The activities are differentiated by the level of evaluation of the testing strategies required. The challenges are presented on the Challenge slides to be displayed on the board, or printed out and placed in the centre of the table. Challenge 1: Children choose a test to investigate the strength of six different magnets Children share their ideas about which activity should be used to test the strength of the magnets. They carry out the chosen test recording the results. They look at their results and put the magnets in order from the strongest to the weakest, and then number them 1–6. Challenge 2: Children assess the methods of testing the strength of a magnet and choose the one they feel is the most suitable and then carry out the test Ask children to try to think of an advantage or a disadvantage of using each activity to test the strength of the magnets. They carry out the test of their choice, recording their results. They look at their results. Which is the strongest magnet? Which is the weakest magnet? Explain how evidence supports these statements. Challenge 3: Children assess the methods of testing the strength of a magnet and use two different methods to test the strength of the magnets and compare the results Children use the resource sheet to record their ideas about the advantages and disadvantages of using each activity to test for the strength of the magnets. Encourage them to try to think of an advantage and any possible disadvantages of using each activity to test the strength of the magnets. They choose one activity to carry out the test, recording their results. They evaluate their Resources: Six magnets of assorted strength per group (ensure that there are some small strong magnets), paper clips, rulers, a range of magnetic objects of different weights (such as keys, cutlery, scissors, cans, tins), paper, measuring scales. Key vocabulary: strength, magnet, attract, magnetic National curriculum links: Observe how magnets attract or repel each other and attract some materials and not others Learning intention: To carry out an investigation comparing the strength of different magnets Scientific enquiry type: Comparative and fair tests Working scientifically links: Reporting on findings from enquiries, including oral and written explanations, displays or presentations of results and conclusions Success criteria: • I can choose a suitable method to use to investigate the strength of magnets. • I can explain why this method is the best one to use. • I can use my results to compare the strength of the magnets. 116
