Review of Magnetic, Electrostatic, and Circuit Models

A few of the students had some trouble with a homework question which asked them to review and reflect upon what our exploration of current electricity so far in class. The question continued, what models of electricity have we considered, and what is the evidence in support or not in support of each model? A couple of the students provided very brief explanations of our exploration, however the work that is required for this class should pull together everything that we've done in that particular week so that students have documentation of what they saw and were able to infer. Also, they are able to reference their work and understandings when they become teachers.

First, we reviewed the two meanings of the word model:
1. Model: a model is built upon inferences and should connect powerful ideas.
2. Flow/Circuit Model: a circuit model should model our thinking about what's happening in a circuit… that something is flowing out of a battery, through a circuit, and back to the battery. The name of what is flowing through the battery = current. A current will flow out of the battery to light the whatever obstacles the circuit has (bulbs).

In a parallel circuit, more current will come out and two bulbs will be just as bright as a single bulb.
Twice as much current is coming from battery when bulbs are in parallel then when placed in series, because there are two circuits being lit.

Modeling Flow Using Pennies (Analogy)
The students traced the flow model with pennies. Emily asked the students to imagine that each penny carries with it some energy, but to realize that the penny keeps going. How much energy the penny carries with it depends on the volts that a battery has. How many pennies are flowing through the circuit depends on what's out there (what obstacles/resistance exists).

Note: Elementary school teachers will have to choose whether to talk about “electrons” as being what is flowing through a wire.

Powerful Idea: Energy is being used up, current is not.