Rob Thompson 2017-03-06 10:56:11
I DOUBT I’m alone in finding that students often struggle the most when learning basic electricity. This article first appeared in my newsletter as the first in a series with ideas for helping teach fundamental electrical concepts using some simple classroom and lab activities. I begin with a class discussion about what students know (or think they know) about electricity. This always brings up common misconceptions and fears students have and is an opportunity to address these topics. During this time we talk about volts, amps, resistance, and watts. Most students have at least heard of volts, amps, and watts. To help visualize and understand what these terms represent, I have the students act out various scenarios related to electricity, such as: To show how resistance affects current flow, each student becomes an electron, and the class tries to rush out a standard door opening. This is then repeated but with the class rushing out of a garage bay door opening. Discussion of the events follows. Once the terms are understood, we start talking about measurements, meters, and circuits. To go along with classroom discussion of circuits, I have the students build and test circuits in the lab using ordinary automotive bulbs and sockets. Bulb types 194, 1156, and 1157 or similar work well. The students are given a handout with different types of circuits that they have to build and test. Examples of these circuits are in Figs. 1–7. I’ve found this approach works well for several reasons: Using automotive components allows students to work on circuits at normal battery voltages. They’re using standard automotive bulbs and sockets found on modern vehicles. By mixing in some “bad” bulbs and sockets, students begin troubleshooting circuit problems quickly. Circuits, such as that in Fig. 2, tend to generate quite a bit of confusion at first but end up as a great example of how voltage drops can really affect a circuit. For this circuit, the students are told the 1157-type of bulb is supposed to work. Students will typically make and test between 10 and 20 different circuits like those shown in Figs. 1–7. The number of circuits depends on the needs of the particular student as some grasp the concepts more quickly than others. Once completed, students then have a pass/fail lab test based on creating, diagramming, and testing a series-parallel circuit. Once a student is able to build, test, and explain the operation of a circuit such as that in Fig. 7, he or she is ready to move on to on-vehicle work. As part of the classroom and lab activities, and to demonstrate how resistance and amperage relate in a lighting circuit, I build a basic bulb circuit and connect a scope. Figures 8 and 9 show a single 194-type bulb with voltage and amperage measurements. Quite a bit of discussion about bulbs and circuit operation can take place just from these images. Rob Thompson is a high school automotive technology instructor, South-Western City Schools, Grove City, OH. He is the author of several automotive technology books and is also a past board member and past president of the North American Council of Automotive Teachers. Reprinted from NACAT News, Summer 2016.
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