Day 121 – Bulbs in Series

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Science 9 – Students looked at how adding more bulbs in series affects the current of the circuit.  They figured this out quite well.  They then were given a reading and a worksheet to apply their new knowledge.

We went through the reading quickly and I pointed out to the students the parts where they should focus their attention.  I think some type of homework/reading quiz may be needed in the future to ensure that students review their readings.

Day 120 – DMV Conservation of Momentum

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Physics 11 – Students used a variety of impulse/collision Direct Measurement Videos today. The goal was to collect data and analyze the total momentum of the objects in the video (system).

A couple of groups got a bit confused because there was missing information on the videos (these videos work towards using conservation of momentum to solve for unknowns). I may need to re-jig how I delegate videos to the groups next year.

Overall the DMV are a quasi-reasonable substitution for not having appropriate lab equipment.

Day 119 – Origin of Charges

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Science 9 – Students used compasses and charging/discharging circuits to see where current flowed in a circuit.  This is a crucial lab to show that charges don’t originate in batteries.  Evidence for this is that charge flows on both sides of the capacitor and charges can’t get past the insulator in the capacitor.  As well, there is current when the circuit discharges without a battery.

This is such a great lab to do but it requires the right classroom culture.  Students have to want to find answers to the questions being asked of them.

Day 118 – Last Day before Break

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Physics 11 – Today the last of my classes got caught up with the momentum activity. Above is an example of student work showing their correct prediction of the force vs time graph, along with calculations for the change in momentum.

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Lots of students were missing today which was a shame because we did some really good group whiteboard work on conceptual questions.

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Day 117 – Capacitors in Circuits


Science 9 – The above video is me going over a lab that the students had already performed.  Sometimes I go over them again quickly to make sure we all have the same consensus on what happened.

Using capacitors in high school science in BC generally is not done. However, we are using them not to learn about time variant current characteristics, but to analyze the nature of charges in a circuit.

The insulator in the capacitor breaks our original model of complete circuits. We get a working circuit, yet we know that charges aren’t crossing through the capacitor. As well, a discharging circuit will light a bulb, so charges can’t originate from the battery. In fact, as shown in the video we must be able to reason that charges are everywhere in the circuit because the compass rotates in all parts of the circuit no matter where the capacitor is.

There is a lot more to say about this topic, but that’s the general idea. These are great activities for the students because it challenges them to reason through logical inferences. Fantastic!

Day 116 – Change in Momentum


Physics 11 – Most of my classes were able to finish their analysis of the colliding cart. I can tell that many of the students are getting really comfortable with moving their concepts and models in and out of different situations, which is really cool.

From their analysis, students reasoned that the “impulse”, or force acting over a period of time, was equal to the change in momentum. We didn’t get into error analysis really, our class time was pretty short today. I might try to have them do another momentum lab to study the conservation of momentum. I do want to have another formal lab report written and graded this time. On the other hand, I am constantly aware of time constraints…

Day 115 – Soldering Capacitors


Science 9 – I made a video for students so they could try out soldering. The end goal here is for students to solder capacitors back to back. I want the students to do this because easily purchased large capacitors are polarized. If a student hooks up a polarized capacitor backwards, it can get fried. By soldering them back to back, we get a non-polar capacitor. The capacitance drops according to 1/Ct = 1/C + 1/C but this drop is ok. And, students enjoy learning a new hands-on skill.