Saturday, November 6, 2010

Posting Seven -- Series and Parallel Circuits

One of the hardest concepts for students in the grade nine applied science course to fully understand is the parallel electrical circuit. I have tried many different approaches to teaching the parallel circuit over the years but it appears that the learners are not yet ready for this concept. This year I took an inquiry-based learning approach and the results were more successful than in the past.

1. Initiate and Plan – ENGAGE

We began our study of electrical circuits with the series circuit. This allowed us to become familiar with the parts of the circuit (load, source, conductors, and switch) and trouble shoot problems that are commonly encountered when connecting the circuit.

Once the class could build a simple series circuit I taught them the symbols used to record their circuits. You can read more about this process in the previous blog entry (posting six). It is also an excellent example of how the conclusion of one inquiry becomes the initial planning stages of the next inquiry.

As an introduction to the parallel circuit, we watched a video wherein both the series and parallel circuits where examined and explained using age appropriate language and examples. Then we watched a simple power point presentation that I created that covered the same ground. Then we took notes, in the form of a t-chart, to compare the two types of circuits. Next, we did a set of questions together, step by step, that covered series and parallel circuits. Finally, for our exit card that day I distributed small recipe cards. The students were instructed to use the appropriate symbols to draw a series circuit on one side of the card and a parallel circuit on the other side of the card. They were allowed to use their note books, text books, confer with each other and check with the teacher during this process (diagnostic or “assessment for learning”).

2. Perform and Record -- EXPLORE

Prior to the next class I went through each of the cards. Using two sets of stickers – big stars and little stars—I assigned groups and which parallel circuit would be built. I used colour coded big stars to determine which students would work together in small groups, students with the same colour big stars would be in the same group. I used smaller stars to determine which parallel circuit I would require them to build –the circuit drawing with the small gold star would be built. In this manner, everyone go two stars—because they are all stars -- yet I got to mix the groups up and control what circuit would be created. The students responded amazing well to this sticker system and seemed quite pleased that I had made at least some of the decisions for them!

It is not uncommon to have some students absent everyday in applied classes at our school. For those students who were missing on the day we made our cards I took a blank card for each of them, wrote the absent student’s name on it and put two star stickers on the blank card – one large one to determine the group the student would be in and one small one, that was any colour except gold!

The next day the cards on which series and parallel circuits had been designed were returned to the students along with the instructions to move into their assigned groups, pick up all the equipment they needed to build the circuit drawing with the gold star on it and go to it!

The students were soon demonstrating their ability to read circuit diagrams, planning what equipment they needed to build their circuits, constructing circuits, using instruments (voltmeters and ammeters), and experimenting to see if they could successfully complete the task.

3. Analyze and Interpret = EXPLAIN

As stated previously, building parallel circuits is very challenging for students in the grade nine applied science class so it was not surprising to me that this task took a lot of time and patience on behalf of the students. While trying to succeed they engaged in constant analyzing, evaluating and reviewing in numerous attempts to get their circuits working. Of the four groups one group finished much sooner than any of the other three. At that stage I dispersed the members of the successful group amongst the other three groups to be their “consultants”.

It was interesting for me to observe many group members using the voltmeters to determine that there was in fact current running through the parallel branches even though the light bulbs were not coming on.

4. Communicate = EXTEND

Now the students took the initiative to test all the light bulbs in their circuits and replace the ones that were not functioning. They even wanted to know the proper way to dispose of the burnt out bulbs!

This weekend I am working on my midterm report cards marks. This class has a mean score of 82%. Now I am worried that my administration will be questioning why my marks are so high! If they do, I shall refer them to this blog!

Here are some videos showing the levels of engagement in the students during this inquiry!

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