More Rigor in Electricity

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Since I have been teaching IPC, the electrical unit has been a paint-by-numbers sort of affair.  We have board with metals pegs, various electrical components that fit over the pegs, and ‘lab’ sheets that say, “do this, then do this, then do this.”  The booklets that came with these kits include questions that are at the most basic level.  The hardest thing about the whole unit was distinguishing Ohm’s Law from the electrical power calculations and inverting the resistance for parallel circuits.

The unit has always seemed like a curriculum afterthought, something to do to keep students entertained during May, after the state test and before final exams.  It has been a yawn fest for both the students and me.

The actual state standards that mention electricity say:

n   Examine electrical force as a universal force between any two charged objects and compare the relative strength of the electrical force and gravitational force.

n   Demonstrate that moving electric charges produce magnetic forces and moving magnets produce electrical forces.

n   Evaluate the transfer of electrical energy in series and parallel circuits and conductive materials.

http://ritter.tea.state.tx.us/rules/tac/chapter112/ch112c.html#112.38

When @whowe67 and I planned the year-long IPC PBL unit, the electro-magnetic standard was the only one that we couldn’t fit into the scenario.  We had vaguely said that we would work it in when we did power, but we started the year not knowing exactly how we would manage it.

This is a great example of the necessity of flexibility when running a PBL unit.  The plans that @whowe67 and I made over the summer were complete, but over the course of the year, many of the units have changed from our original concept.  Some have been a natural change as we’ve gotten a better idea of the how the year is progressing, and some of it has been at the request of the students.

In the case of electricity, when I was writing the power unit, I realized that electricity would fit into it perfectly.  The challenge for the students became, “How can we design a way to turn a turbine that will generate electricity, given the resources on the island?”

The sources of power on the island would be wind, tides, geothermal, solar, and hydroelectric.  We bought lots of copper wire and magnets, so the students could make simple generators.  The challenge here was two-fold – use one of the renewable resources to move the turbine, and build a generator capable of turning on a tiny light.  The students would use their previously built shelters and wire them either in series or in parallel.

When the students had to actually build an electrical generator, we had many conversations about the very basics of electricity – what it is, how it moves, what a magnet does to electrons, and how the forces between the two interact.  They went far deeper into the concept than I have ever seen in my years of teaching IPC.

Not all the generators were successful.  Some could only measure the electricity produced with a sensitive multi-meter.  But the struggle to design and redesign is where the true learning took place.

We still covered the series versus parallel issue and electrical calculations, so they weren’t missing anything from what students in previous years had done.

What we gained was an enduring understanding of the concept and a way to apply it to other situations.  I have never felt that the electrical unit was rigorous enough until this year.