Mechanics Modeling Instruction Reflection

I just finished my second year of Modeling Instruction for mechanics in my regular physics class.

While I attended a mechanics modeling workshop a few years ago, I remember when I first decided to jump into modeling with both feet. I was looking at a problem involving electromagnetic induction that required use of the equation F = BIl. All students had to do was to find three numbers, one in units of tesla, one in amps, one in meters and multiply them together without any understanding of physics. This was reinforced when I saw students in the next question trying to solve for resistance using Ohm’s Law and plugging in a velocity instead of a voltage. Many of my students weren’t understanding physics, they were learning to match variables with units and plug-and-chug. Our curriculum was much wider than deep and I felt that I had to make a change.

Fortunately, my desire to change the emphasis of the curriculum coincided with a county-wide effort to define a core curriculum for physics. While it wasn’t easy, the team of physics teachers at my school agreed that we had to at least cover the core curriculum as defined by the county effort. This was the opportunity to reduce the breadth of the curriculum, focus on understanding and critical thinking, and use Modeling Instruction for mechanics.

I felt that the first year of Modeling Instruction was a huge improvement in terms of student understanding. This past semester was even better. While just one measure, FCI gains reinforce my beliefs. In 2009, the year before introducing Modeling Instruction, my students’ average FCI Gain was .33. In 2010, the first year of Modeling Instruction, it was .43. This year, the FCI gain was .47. While I don’t credit Modeling Instruction as the sole factor that produced these improvements in students’ conceptual understanding, it is probably the most significant. We also started standard-based assessment and reporting in 2010 and, hopefully, I’m improving as a teacher in other ways. For me, the most important confirmation that I was on the right path was that I couldn’t imagine going back to the way that I was teaching before.

The three most important changes that I made this year were: [goalless problems](, sequencing of units (CVPM, BFPM, CAPM, UBFPM, PMPM), and [revised Modeling Worksheets]( based on the work of [Kelly O’Shea](, [Mark Schober](, and Matt Greenwolfe.

There is still plenty of room for improvement, however. Pacing was a big issue. We still have to finish mechanics in one semester. As a result of the time spent in other units, I really had to rush energy and momentum. While students could connect to many concepts in the momentum unit with previous models, energy was completely different. However, this experience had a silver lining in that it may provide hope for other teachers who want to adopt Modeling Instruction but are concerned that they won’t have time to cover their curriculum. I decided at the beginning of the semester that I would spend the time I felt was needed on each unit to develop the underlying skills of critical thinking, problem solving, and conceptual understanding. When I got near the end of the semester and had to fly through energy, I didn’t introduce it as another modeling unit. Instead, I presented it to the students as another representation of mechanics. I encouraged them to apply their critical thinking and problem solving skills to this different approach. I was pleasantly surprised when they did as well as previous years’ classes on the energy summative exam despite the incredible short amount of time we spend on the unit. I think this supports the idea that students versed in Modeling Instruction will have a strong foundation that will allow them to readily understand unfamiliar topics as well as, if not better, than students who covered those topics in a traditional fashion.

Whiteboarding continues to be an area that requires improvement. I made a couple of changes that improved the level of discourse among students. When whiteboarding labs, I either explicitly jigsawed the lab activities or guided groups to explore different areas such that each group had unique information to present to the class. This variety improved engagement and discussion. When whiteboarding problems, we played the mistake game on several occasions. This too increased engagement and discussion. However, I feel that I still have a long way to go to achieve the socratic dialog that I believe is possible.

Next fall, I will dramatically shorten the first unit which focuses on experimental design and analysis. I will probably still start with the bouncing ball lab but then immediately move onto the constant-velocity buggies. That should allow enough time to explore energy and momentum in a more reasonable time frame.

At least I feel like I’m on the right path.

3 thoughts on “Mechanics Modeling Instruction Reflection

  1. Kelly O'Shea

    What did you think of the BFPM / CAPM flip?

    How long did you spend on PMPM? I spend the least time there, but a (relative) lot of time with energy.

    I do momentum before PMPM. I think it helps shorten PMPM (since it is basically old news by that point). Do you do 2-D momentum? Without the 2-D parts, that can be a fairly short unit, too (the shortened version is what we do in my regular classes).

    1. geoff Post author

      I am sold on the CVPM, BFPM, CAPM, UBFPM, PMPM sequence. I think the idea of modeling what you have observed and then focusing on “the why” ties one unit smoothly into the next.

      I spent two weeks on PMPM. I could have spent less, but I wanted to try the Angry Birds project. I would be tempted to do momentum before PMPM, but the reason that I do it last, for better or for worse, is it is the least significant part of our curriculum and shared final exam. If I run short on time and abbreviate momentum, it is not as much of a problem than if I run out of time on PMPM. In my regular class, which this is, we do not do 2D momentum. We only cover 2D momentum in honors. I’m working on a post reflecting on my semester with honors.

      1. Kelly O'Shea

        AHH! My regular class is only going to get halfway through momentum (unit 5) before our exam!! My honors class will finish energy. :/

        And it’s a shame that the test is dictating PMPM over momentum when momentum is obviously (well, in my opinion, anyway) worth more time spent understanding :/


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