## Day 121 – Bulbs in Series

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

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

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

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.

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

## 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.

## Day 114 – Colliding Carts

Physics 11 – As an introduction to momentum, I have a cart interacting with a force sensor. We dug out an old airtrack and it seems to work pretty good for this. The gif above shows carts colliding on the airtrack.

As for the activity, students make a prediction as to what a Force vs. time graph would like like. I was very pleased and impressed that the students overwhelmingly made a good prediction. Note: sometimes it is not good to make predictions as they can help reinforce misconceptions!

I had a force sensor for this activity but not a motion sensor. I was able to hook up to the Pasco DataStudio software and show the class the F vs t graph. I then had students compare the area under the graph to the change in momentum. To find the momentum, the students were given the mass but they needed to analyze video to get the velocities. That’s about as far as we got today.

## Day 113 – Pro D New Curriculum

Science 8 – Today there was a province wide professional development day for learning and collaborating about the new curriculum. The above graphic is from the science 8 curriculum. One thing I noted on this day was the importance of the kinetic molecular theory. I believe it will be a crucial unit for going through the curricular competencies. This is the unit where students will be using mass balances, graduated cylinders, collecting data, graphing, etc. I think that topics such as density, viscosity and pressure will all fit into this part of the curriculum. While I don’t think that learning viscosity has any large importance for students, it is clearly a good topic to investigate in order to learn and master certain process skills.

As an aside, a friend told me a story about the kinetic molecular theory. Apparently Richard Feynman was asked about what he thought would be the single most important idea or theory that should be passed along to a new civilization, if we could pass on only one. His answer was the kinetic molecular theory: that all things are made up of small particles which vibrate faster as they heat up. Or something like that. Anyways, it’s important.

## Day 112 – LOL Instead of Work-Energy

Physics 11 – By using the LOL diagrams, students do not need to conjure up the Work-Energy Theorem. Instead, students can use first principles: by analyzing the LOL diagram and coming up with the conservation of energy equation, students can solve for any unknown. The work-energy theorem, while concise, is one extra level of abstraction that probably isn’t needed at this point. What is more important: that a student can plug numbers into the right formula or figure out what is happening with energy in the system? These aren’t mutually exclusive, but abstractions can lead to answers with understanding.  This is seen all the time in math, physics, programming, etc.

For problem solving, each step is simple and achievable but these are multi-step questions. They can be difficult for students while they learn to assimilate several ideas at the same time.