Simple Circuits Curriculum

Section 6: Background Information

Analyzing Parallel and Series Circuits Using the Cyclic Simultaneous Model

Students generate explanations, starting from whatever model they hold for the simple circuit, to explain why bulbs behave as they do in series or in parallel circuits. Their underlying models can be so strong that sometimes students actually perceive what they expect to see happening and are unable to see what really happens in their experiments. Therefore, it is important to have students discuss their various ideas and share what they think is going on. It is important to give them opportunities to use the Cyclic Simultaneous Model to explain what happens with bulbs in series and in parallel because it helps them to focus on the system as a whole, not just on local features of it. An example of this is focusing on what happens to each bulb separately, as opposed to what happens to all the bulbs together as a system.

The Importance of Presenting AND Critiquing Analogies

Further, the analogies that teachers often use to explain the simple circuit can lead to new misconceptions or support ones that students already hold. For instance, the "water in a hose"model, presented in this lesson and commonly used in units on electrical circuits, furthers the notion of electricity as substance-like rather than process-like. While this model can be useful in helping students to think about the relationship between voltage and current, the potential misconceptions it introduces also need to be discussed. One could just decide not to present potentially problematic analogies to students. However, when analogies are common enough, it is likely that students will hear them at some time or another. Therefore, it is better to address the embedded cognitive challenges in the analogy rather than avoid it altogether.