Choosing a teaching approach
Thinking about the teaching
Planning to teach about the connection between charge flow and current leads to a necessary choice of teaching approach, which involves either:
Starting with measurement: The pupils are told that ammeters measure electric currents and that they are to use an ammeter to find out what they can about current values at different points in circuits; or
Starting with the electric circuit model/teaching model: The concept of electric current, as charge passing per second, is introduced (drawing on the teaching model) and the pupils are instructed to use this idea to make predictions of electric current values at different points in circuits.
Starting with measurements, in this particular context, does not make much sense to us, since the pupils are being asked to make measurements of
currents when they have no idea of what an electric current is.
The approach which we suggest, therefore, is to:
- Talk through the electric circuit model, and teaching model, with the pupils
- Demonstrate how to use an ammeter to measure an electric current
- Encourage pupils to use the model to make predictions of the value of the electric current at different points around various circuits
- Get pupils to check their predictions through practical measurements with an ammeter.
In this way, the practical measurements are used to confirm the developing electric circuit model, helping to make it seem plausible and fruitful for the pupils.
A very practical advantage of this approach is that the pupils set about making measurements of current with the expectation (hopefully!) that the values of the current will be the same. If the instruments indicate slight differences, these are likely to be accepted as being
just about the same.