Day 38 – Concrete vs Abstract



Physics 11 – Students have a really hard time interpreting graphs like the one just above this text. Once they get good at the mechanics (procedure) of the interpretation, it can be done easily and quickly. My co-worker thinks students struggle because they don’t have a procedure or set of steps to do this type of task. I agree. We could give them a procedure, but what would be the point?

Today I quizzed my students on this learning objective again (graphing constant acceleration motion), using questions like the first photo above. This gives the students a concrete idea of what the motion is. It’s easier, and while I would hope that all my students can do the 2nd graphing task, I believe that it’s the first one that we really care about.

Day 36 – Working with Graphs

Physics 11 – We’ve started working with kinematic equations but before we got too deep into that, I had to go over graphing a bit more. Students really struggle with this topic. One reason for this could be that lots of the practice graphs I have them work with are really abstract in nature and don’t really describe any realistic motion.

It was time for Peer Instruction, and the above question and results were normal for the day. Vote #2 had a much higher correct answer rate.

Working with kinematic equations have brought forward two certainties in the physics classroom. Certainty #1 is shown below, and the question drives me crazy.


Certainty #2 is that students automatically go to equations to solve their problems.

I also saw people replacing variables in the work with an “x”. When asked about this, students said they are used to solving for x. So. Much. Work. To. Be. Done.

Day 16 – Mistake Game

Physics 11 – Today was the physics’ students first shot at the mistake game. The above picture shows a group’s work on a ranking question.

As well, I handed back last day’s quiz on graphing, best fit lines, slopes and models. I asked students to look at three other quizzes to compare mistakes. They then had to write down the three most common mistakes and hand this sheet in to me. This is my attempt to stop them from repeating the same old mistakes time and time again…

Day 61 – Direct Measurement Videos


Physics 11 – In preparation for the paradigm lab for unbalanced forces, today’s physics classes used Direct Measurement Videos (DMV) to analyze constant acceleration motion of a toy car.

The DMV we used were from Peter Bohacek at Carleton.  They are, simply put, brilliant.  Peter started making these videos a few years ago and in their most basic form, DMV are quite simple.  You shoot some video of an object moving and make sure there is some type of ruler in the scene.  Better videos will be shot at higher frame rates with better lighting, better apparatus and setups with very little lens distortion or perspective.  Once you have a video, you can analyze time (counting frames) and position.

Peter’s newest videos are put into an html5 video player with many more features.  For today’s class the DMV player we used allowed the user to pick different toy cars to analyze.

It took the whole class for students to get used to the software and gather data for analysis.  They were asked to find the acceleration of the toy car, but lots of students started collecting massive amounts of data and plotted position vs time graphs.  This was after we had a class discussion on how acceleration can be calculated directly from d = vot + 1/2at^2, or a = dv/dt, once you find the beginning and final velocity.  I’m not sure I’ll ever quite understand how students get off track so often (well, I think I know why, I just don’t know if I’ll ever get good enough to mostly eliminate it).

Day 40 – Buggy Challenge #3


Physics 11Taken right from Frank Noschese’s blog…  I’ve gotten so many great ideas from Frank.

Students needed a lot of help with this.  I wonder if this type of activity should begin with an extensive group discussion involving the whole class?  The problem I see with this is that it allows some of the stronger students to easily dissemminate the solution to the rest of the class.  Given that the solution is not the most important part of the activity (it’s going through the process of getting the solution), I’ve always let students struggle with this type of task.

Cognitive Load theories and direct instruction teachers would probably say that each group finding their own solution is inefficient and doesn’t give any direct benefits or learning.  They might be correct, but I am sure that being shown/told how to do this type of problem, and then practicing it until they are proficient at doing it, is not any better.

Day 38 – BFL

two motions

Physics 11 – Today was another A-Ha! day for me. It became apparent to me that my physics students were utterly confused on when to draw a best fit line and when not to.  I had seen warnings of this, but today I found just how confused the kids were.

Starting with constant velocity, we used graphs to tell the story of an objects movement – moves forwards fast, slows down, stops, then moves forward again, etc.  When conducting experiments, we collect position and clock reading data, plot the data, and analyze using best fit lines on linear relationships.  To the kids, this is all lumped into the category of “graphing” and they’re not sure when to draw lines from point to point, and when to use a BFL.

I went over the topic, talking about constant motion vs story telling, but I don’t think many kids really got it.  There was a lot of head nodding, but still a lot of confusion I think.  This is also the time of year when we really need to move on.  It’s just not worth getting into an endless rut of graphing.

So the real question is, how to motivate students that don’t get it, to come in for extra help and get past any hurdles they are experiencing?

Day 36 – The Mistake Game


Physics  11 – Today the physics classes did group whiteboard problems and presented their work to the class.  We used the Mistake Game, where each group had to include a mistake on their whiteboard.  In the above example students did not convert from km/h to m/s.   It was a great way to reinforce the idea that we have to work with common units when doing our calculations.