Modeling Workshop – Day Three

Work continues apace on our unit. Our desire to develop no less than five models (balanced torques, constant torque, rotational inertia, angular momentum and rolling motion) has had to face reality and deal with the fact that the workshop is only another 11 days long. I believe we will restrict ourselves to fully developing the curriculum for the first three models above, but attempt to include as many notes as possible for the other models.

While much of the day is devoted to working in our small group and fielding questions from the workshop leaders, we did come together as a class for two discussions. First we tackled the questions of “What is modeling?” and “What makes modeling modeling?”. That first one is a tough one to answer. I’ve always relied on simply describing the initial pendulum unit to convey the difference in how the class is managed and constructed. As other teachers mentioned today, you still get responses like “Oh, I do a lot of labs/demos in my class too.” or “Oh, that’s inquiry learning.” which both miss key components of what the modeling cycle entails. One of the best responses today was that modeling is a way to organize your curriculum. Everything you do, from development to deployment, including assessments, is directed toward explaining, refining, testing and breaking the model and so, the model must be the core component of the curriculum.  This means that if you want to develop a new modeling unit, the first question you have to answer is “What is the model I want my students to build?” repeatedly followed by “How does this question/activity/lab address the model?”.

The other discussion was about our article reading. Two articles were assigned this time – one on the role of the lab practicum and the other on context rich problems. Now, I love lab practica and try to include one in every unit we study. I think they are a fantastic means of assessment (though I don’t grade them) and they push students to really develop confidence in their initial model development. Context rich problems though rub me the wrong way. They seem filled with unnecessary and unrealistic context, at least from my limited exposure to them. Here’s an example:

Roller Splash: A company that designs amusement park equipment asks you to design a new roller coaster splash ride. A cart with passengers starts at rest and rolls down an inclined track to a horizontal section at the bottom where it flies off to land in a pool of water – what fun! For more excitement, physics students using the ride must decide their starting position in order to land safely in the water. You are asked to build and test a miniature model. For this model, determine the position of the Hot Wheels track that a Hot Wheels car should start so that when released it moves down the track and flies off the horizontal section to hit the target on the floor.

So much of this bugs me. First, all of these seem to be couched in terms of “you work for a company…build a miniature model”. Unfortunately, your miniature model is nothing like the real ride. It doesn’t account for weight distribution of people (How many people are on the ride and does their weight matter?), drag forces, rolling motion, how you would get this rolling car out of the water and more. By dressing it up this way, the author seems to be indicating that this topic isn’t interesting to students normally, so we’re going to try and make it interesting with some flavor text. You don’t need to describe a “bungee jump system that provides the jumper the extra thrill of just missing the ground” (because no company would ever actually build this!), just hand the students a spring and an egg and say “Okay, you’ve all learned about energy and springs…decide how high to hang your spring so that when I give you a 200 gram mass to attach at the end and drop, it doesn’t crack the egg lying directly underneath it.” They will work so hard to protect that egg and the excitement in the room will be palpable when that first student lets go of the mass.

Now, I’ve heard good things about context-rich problems elsewhere and I like the actual activities as they are really just lab practica. So, what am I missing? Why is that silly context so important? Or isn’t it?



  1. I have to say that the thin backstory to context-rich problems has always bothered me, as well. After awhile they all read the same, at least in my opinion. I like your spring-egg problem. Maybe it’s not “real world” enough for some, but you are right that the students would totally get into it. Maybe as a part of that problem, you can ask if there are any larger applications of what the students calculated. And, if so, what additional elements must we include? I call that “complicating the problem,” and only a few of my students end up being able to really do this on their own (some without being prompted). I guess this is stretching the kids to create their own contexts.

    Perhaps this is all related to the question of “relevance.” What’s relevant today will not necessarily be relevant in the future. Instead of trying to make content relevant, shouldn’t we be helping students to be able to create their own relevancies?

    1. Thanks for the reply, Mark.

      I like your idea of prompting the students to find “real-life” context beyond the classroom. My students are always very excited to share their discovery of a phenomena outside the class that relates to what we are studying. Relevance is a strange thing, and I’ve lately been thinking that it’s overemphasized. Consider the Vi Hart math videos. Students love them. At least mine do. But those videos cover content that is certainly not relevant to “real life”. What Vi does so well in the videos is express the joy of learning something simply for the sake of understanding. She shows that it’s fun to learn things. I think physics can do that and create better problem solvers at the same time.

  2. So yes, I’m creeping, but read this and had to comment. The context problems have always seemed ridiculous (and I speak for myself and my fellow classmates, here), and I would be so much happier with the egg-spring experiment than with a condescending word problem. I would work so much harder with a physical model like the egg-spring experiment in front of me, and success in that case would be much more rewarding than checking the back of the book and making sure the answers match.
    Basically, I completely agree. This is why everyone loves your classes.

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