Simple Circuits Curriculum

image of christmas lights

This lesson asks students to interpret parallel and series circuits using the Cyclic Simultaneous Model. It uses a number of analogies to help students see the relationships involved in a simple circuit.

Section 6: Understanding Goals

Subject Matter

  • When you arrange two bulbs in series, they will shine less brightly than if there was only one bulb. They will also shine less brightly than if they were arranged in parallel. This is because there is less current in the circuit due to greater resistance.1
  • When you arrange two bulbs in parallel, they will shine as brightly as if there were only one bulb. (If you keep adding bulbs in parallel, eventually they will get dimmer due to the voltage of the battery.) This is because the amount of resistance for any single complete battery and bulb circuit stays the same. (Each bulb is, in effect, connected directly to the battery.)

Causality

  • Using a Cyclic Simultaneous Model to reason about series and parallel circuits helps us to focus on what happens across the system as a whole, rather than focusing locally at each bulb.