3. Modelling electric circuits
Difficult ideas can often be helpfully illustrated using a physical analogy. This can make something that is very abstract feel concrete and can help the students to understand. The danger, of course, is that an inaccurate physical representation can introduce more misconceptions and difficulties at a later stage. When you are using physical analogies, you should always get your students to discuss the merits of the particular model. By identifying the shortcomings of the model, you will also add to their understanding. In the case of electricity, there are two models that you can use. The teacher in Case study 3 has tried role play before and feels confident about using role plays in her lessons. She uses both models and encourages her students to decide which one is the best. Activity 3 describes a role play that your class should enjoy. Resource 5 provides some example role plays and instructions for carrying them out.
Case study 3: Evaluating models
Miss Chitsulo is a student teacher. She wanted to use a role play exercise to explore models with her students as one of her college assignments. She decided to try out two different role plays with her class, so they could discuss what is good about each model. First she tried out the ‘sweets and cups’ role play with a group of students. She checked that everyone in the class understood how the role play models what is happening in an electric circuit. She asked the students who were watching to explain what each part of the model represents. Then she used a different group of students for the second role play, which uses a rope loop. When they had tried both role plays, Miss Chitsulo asked her class to compare the two.
She asked some questions: ‘Is this a good model? How is it not so good? Why do you think that? Which one did you find easier to understand? Which one would you use if you wanted to explain about circuits to someone of your own age who had not learnt about them?’ Her students enjoyed the role plays and were pleased to be asked their opinions. Miss Chitsulo’s tutor was pleased that she had got her class so involved in thinking about a challenging topic.
Activity 3: Organising a role play
Choose one or both of the role plays described in Resource 5 and prepare your resources before the lesson. For the ‘sweets and cups’ role play, you will need two paper cups, two boxes, and a packet of sweets with wrappers and for the ‘rope’ role play, you will need a rope two or three metres long, with the ends fastened together to make a loop. Explain to the class that they are going to use a role play to model what happens in an electric circuit and that at the end of it you will want them to be able to describe the model and what things it helps to explain. Choose students to take part in the role play, and ask everyone else to watch and listen carefully. Ask questions about the role play as it is going on. Get the students to explain which aspect of the circuit is represented by the different parts of the model. At the end bring everyone together to discuss the strengths and weaknesses of the model. Ask everyone to write a short paragraph to explain the model in their own words.
2. Discussing key ideas in groups
Resource 1: Common Misconceptions