Day 89: Working on Work


Physics 11 – Working on Work was the topic for the day.  We had discussed in class how working is the idea of transferring energy into a system. As well, I had introduced the idea that energy is the area under a Force-displacement graph.  From this, it was relatively easy for the students to grasp that W=Fd.

The formula itself is easy to grapple with.  However, the nuances need clarification.  So went through 4 examples to illustrate 4 main points:

  1. Work is calculated from applied forces, not a net force
  2. Something has to move in order for there to be work. I briefly explained that even a transfer of heat is a type of work, where the “thing” that moves are all of the particles (as per the Kinetic Molecular Theory).
  3. We only need to consider the component of the force that is in the same direction as the movement
  4. Work, while being a scalar, can be represented as a negative quantity which refers to a transfer of energy out of a system.

After going through the examples, the class then did some Peer Instruction with Plicker cards.  One class went from 50% correct to 98% correct. The second class improved but still need an intervention – it went from 40% correct to about 60% correct.


I won’t use this question again, though.  There is in fact a small bit of horizontal force acting on the mass equal to the force of friction between the mass and the hand.  If μ = 0.1, then Ffr = 0.2 N, and the work done would be 0.4 J.  Only a few students asked about this, so I guess for one more year I avoided confusing too many people.

Day 88: Professional Development Day


Pro-D There are no classes today because of our district’s professional development day.  I scheduled to give a workshop on Standards Based Grading, but only 2 people committed to attdending.  Because they live from quite a distance away, they (rightly) decided to pass on this opportunity.

Part of me says that I should keep offering to do a workshop on SBG, but another part of me says that nothing will change. I guess teachers around me are very content with their grading systems.  I don’t think most of them know any other way, but there you have it. I’m always surprised by this. It took me less than a week of teaching to realize there was something drastically wrong with the typical gradebook approach.

Day 87: Assisted Reproductive Technologies


Science 9 – Today was the start of some research and writing on assisted reproductive technologies.  Specifically, I asked the students to produce a persuasive essay.  The handout I gave outlined 8 questions or ethical dilemmas around assisted reproduction.  Each student has to decide on a question that they will take a stance on, and write an essay on their reasoning.

I framed the persuasive essay as an assessment tool that tells me about their scientific understanding of the topic, along with getting them to use critical thinking.  The students were very engaged in this activity.  We went to the library to use iPads and the wireless internet for their research, and most students managed to stay on task (a bit of an accomplishment in grade 9 I think).  I’ve asked the students to tell me about the technology, pretending I don’t know anything about reproduction, and then to persuade me that their stance on the issue is the correct one.  Several students weren’t sure how they could use research to justify their position. I suggested that something like a Wikipedia article may not support an argument one way or the other.  However, they can research newspapers or other media for opinion letters and use this for reference material.

Day 86: Curved Mirrors


Science 8 – The students continued looking into light and optics today.  The main goal was to see how curved mirrors affected light rays. Unfortunately we don’t have curved mirrors to use with ray boxes so I improvised using curved aluminum foil.

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I think this activity is a bit difficult for the students but it is hard to assess. I don’t want to go deep into them drawing ray diagrams, I mainly want them to understand how mirror curvature and focal points work, and how the images change.  The other part that I am concentrating on is the idea of communication competency.  By this I mean that the skill of drawing a clear diagram using a ruler is an important part of communication.  Whether the student is doing a diagram for themselves, for their teacher or for their classmates, it is important to do a good job so that they can exchange their ideas.

Day 85: Life Story

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Science 9 – Having starting looking at mating and fertilization, I thought today would be a great time to show a video on mating from the new BBC series “Life Story.”  The series has great videography and this episode is right on track for the science 9 course.  The students get to see the advantages and disadvantages of internal and external fertilization and the different ways that animals mate.  But most importantly, the show is just COOL.  Above, check out the amazing pattern created by a pufferfish for attracting a mate.

Day 84: Energy Bar Charts


Physics 11 – I was introduced to energy bar charts through the physics modeling program, and it is one of the best things that I’ve introduced to my students.  So much of the conceptual material for energy in physics 11 is covered with these bar graphs.   All that is missing is the algebra and calculations.

The students were really engaged while working through practice questions on bar charts.  I think this work really hits the sweet spot for the Zone of Proximal Development for the majority of students.  The charts are new, thought-provoking and manageable.

I have been following the modeling curriculum fairly closely until now.  I’m not equipped to do any experiments with energy.  Rather, I’ll be use direct instruction that that the area under the curve of a Force-Displacement graph is energy. This will lead into the concept of working, and the formulas for gravitational potential energy and kinetic energy.

Day 83: Reflection and Refraction Activities


Science 8 – Today the students worked through three stations to observe and record what happens to light when it passes through different mediums.  The first activity has the students look at light that reflects off the top surface of a beaker of water.  Kind of cool but not jaw dropping.

The second activity to be fun, interesting and good one to explore and engage with.  They used a ray box to refract light through a glass block.  This one gave the students lots of opportunities to see what light can do.


The shocking activity was the last one.  Students look towards a jar lid that has a penny in it.  They lower their head so that they cannot see the penny. Then a partner slowly pours water into the lid and all of a sudden the student can see the penny because the light is refracting as it comes out of the water.

Day 82: Energy and Pie Charts


Physics 11 – Energy has been introduced in physics 11.  So far the students are focusing on the idea of energy storage systems as opposed to something “having energy.” I used a couple of quotes from Richard Feynman to stress that we have a really hard time describing exactly what energy is, but we are not bad at saying where energy is stored.

It is important to realize that in physics today, we have no knowledge what energy is.

Do not keep saying to yourself, if you can possibly avoid it, “But how can it be like that?” because you will get “down the drain,” into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that.

The students were really engaged during this activity and the students demonstrated good critical thinking.  Without detailing it, this work touches on both the First Law of Thermodynamics (the total amount of energy doesn’t change) and the Second Law of Thermodynamics (Dissipated energy never goes down).

Day 81: Consolodation of Sexual Reproduction


Science 9 – Today was a pretty dry day.  Students were prompted to focus on two learning objectives, and had their choice of activities that they wanted to work on.  I think that a realistic view needs to be taken with students in grade 9. I don’t believe that small details of meiosis are very important for the students to memorize.  It’s the big ideas that they need to know: sexual reproduction results in genetic diversity, meiosis produces gametes with n chromosomes and diploids with 2n chromosomes, etc.  It’s also good to read about the details that makes these big ideas happen, but ultimately we don’t need to assess the small details.  How do I know that I’m sure? I can ask any grade 10 student, even the top students, and they don’t remember the details.  They have no lasting impact.

Day 80: Law of Reflection


Science 8 – I showed the classes a video of pool balls bouncing on a pool table.  From this, the students were broken into groups and asked to come up with a rule that describes the path that the balls travel when bouncing.  They wrote their rule down on whiteboards, and almost all groups independently came up with the Law of Reflection.  A few groups wondered if the ball always bounces back in a 90º angle.

The students were then asked to shift their rule over to the reflection of light. On their whiteboards I drew where I would place a mirror and a laser. They had to predict the path that the reflected laser would take.  Most students did not have a protractor, but most came pretty close.  The photo above shows one group that came very close.