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There is a great new video ‘wall’ started by Peter Vogel, for the British Columbia Association of Physics Teachers, called BCAPT Wallwisher of Favourite YouTube Physics Videos: http://www.wall...bcaptvideos.

One of the videos is quite lengthy, but I enjoyed all 120 minutes of it: Eric Mazur: Confessions of a Converted Lecturer. Eric’s bright Harvard pre-med students rated his teaching very favourably, but when Eric decided to find out whether his physics students really understood basic concepts of force (e.g., Newton’s Laws) he was very disappointed in the findings. His students, taught by conventional lecture methods, were good at ‘chug-and-plug’ test questions, but not so good at questions that required a deeper understanding of concepts such as Newton’s Third Law, for example.

Professor Mazur’s solution was to include peer discussion in his presentations. Groups of students discussed situations he presented among themselves (peer discussion) during the lecture hour, instead of just listening to the professor and taking notes.

Experienced science teachers know that through practice and repetition, science students can do very well on examinations, and yet possibly not have a true ‘feel’ for, or a deep understanding of the subject. The approach that ‘handson’ science teachers advocate for secondary and elementary science learning incorporates ‘peer discussion’ to a degree (since they work in pairs or other small groupings), but goes a step further. Students work with real materials, hopefully just about every science class.

Here is an example of a lab-based’ (i.e. ‘hands-on’) activity, using very simple electric circuits.

Set up Circuit 1.

Observe the brightness of the light bulb and measure the amount of current in the ammeter, in milliamperes.

Make a prediction! If a second light bulb is connected in the circuit, as in Circuit 2, will each of the two light bulbs be

(A) about half as bright as the light bulb in Circuit 1, or

(B) about the same brightness as the light bulb in Circuit 1, or,

(C) much brighter than the light bulb in Circuit 1?

Make a prediction! When the second light bulb is in the circuit, will the current measured by the ammeter be

(A) about half as much as in Circuit 1, or

(B) about the same as in Circuit 1. or

(C) about twice as much as in Circuit 1?

Now set up Circuit 2. Test your predictions.*

To some students, the results will be ‘counterintuitive’. (“If you add an ‘extra resistor’, should the current not be less, and

the light bulb less bright?”) In this type of question, there is no ‘recipe’ you can find at the back of the test paper. You

have to understand how parallel circuits work. Students (and teachers) who have worked with actual circuits for any length of time will know what happens. Students who have learned physics just by ‘taking notes’ will have less success with their predictions. If the result is counterintuitive, it will make the student ask, “What goes on here?” He or she is now ready to learn and truly understand.

*Experimenting with the real circuits reveals the answers (B and C).