Task 18

The teacher can build on the results of the 16th task. In this task, the pupils found that if two objects rub against each other, a larger friction force arises that slows the movement of the object. Teacher reminds this result and suggests to try it. He can present a research question by considering this finding: a larger object is rubbed with a larger surface area, even it is heavier and thus pushing the surface more and he thinks it is more difficult to move that object. By doing so, he gives pupils an example of how to identify questions for further investigation. He suggests exploring the friction force using magnets. Pupils will attract a paper clip by a magnet, comparing whether the magnet attracts a biggerpaper clip later (from a smaller distance) than a little one, assuming that the larger paper clip would rub more on the paper. For pupils, this task has a deductive character, as their task is just to verify the validity of the underlined explanation.

Pupils therefore do not make predictions, but merely carry out measurements as suggested by the teacher. The same magnet is approaching the paper clip that is positioned exactly where it is drawn. When the paper clip moves toward the magnet, they mark from which distance it has been pulled. They will do the same measurement three times for a smallpaper clip and three times for a big one (the worksheet is formulated to guide them). The pupil gets the data in a graphical form, so it is easy to evaluate whether the bigger one is drawn from the same distance as the smaller one or the smaller one. Pupils then formulate a conclusion in which (based on what results they have obtained) they comment on the confirmation, respectively. not to confirm the thesis.