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physics, teaching

How to Practice Physics (By Really Trying)

I want to do a better job of teaching my students how to practice physics. When I tell them which skills need work (see the SBG tag for more details), I want them to have some ideas about what it looks like to practice those skills. We say practice, not study: practice definitely means there’s a pencil in your hand (no pen in my physics class because you’re required to make mistakes) and a new piece of paper in front of you.

Time to grow some myelin

Here are some ideas that I’ve given students in the past. I’d like to keep adding active, quick, obvious (that is, easy for kids to see what to do and get started on them right away, even though the work itself isn’t easy) ideas to this list. Cover up your work and try the problem again without seeing what you did before is a clear one (one that some, but not all, of my students think to try anyway). After you’ve done that, you can:

  1. Work the same problem again, but this time add the answer to the given information and take away something that was originally told to you. That way the problem is new, you won’t be just using the same procedure with different numbers, but (and here’s the really great part of this strategy) you’ll immediately know if you did it wrong because you already know the new “answer” to the question.
  2. Go back to old units. Rework an old problem using newer models. Do they apply? Do they work as well? Better? (Example: go back to the momentum unit and see what happens when you analyze the collisions and explosions using conservation of energy. Go back to the unbalanced forces unit and use energy and/or momentum to analyze the problems again.) This strategy works especially well for the goal-less problems in the old units. Look at what you didn’t know you would be able to do, back in the day! If you have too many unknowns, try making up one more piece of information at a time.
  3.  Turn the problem into a goal-less problem. Add more information, one piece at a time, if you have too many unknowns. Goal-less problems build in so much extra practice, it’s crazy. Now that we work these problems often, my students have probably drawn hundreds more graphs than they would have drawn just to solve the problems. They also seem to be a lot better at drawing and using those graphs when the time comes, too.
  4. Play with the model until you break it. Example: how many different ways can you define your system while you are solving this energy problem?Most students start with the pig and earth (and, if it is early in the unit, also the hill) inside the system. But what happens if you take the earth outside of the system? What if you put the hill outside the system? It is delightful when both of those work out to give you the same answer. Now, what if you take the pig out of the system? They try to draw the LOL diagram and poof, the model is broken.

Can you do this by watching a video?

I’ve reread Mark’s post on deliberate practice, and something about it keeps bothering me*. His descriptions of practice in swimming almost all involve the swimmer in the pool, actively working. But the descriptions of practice in physics (he describes how his students use the videos he occasionally makes for them) don’t strike me as very analogous. The physics students are not as actively engaged in doing physics as the swimmers are in swimming. If anything, they seem a confirmation of the inefficiency involved in learning by watching.

It seems to take many watching to begin getting value out of the process. Once that value is achieved (aha, now I get how this problem works, how to add vectors, etc), it is hard to imagine a student watching that same video many additional times (as opposed to something from the list above, which they could keep applying to the same or different problems). It is easier for a student to watch a video about a problem or a skill and feel that they “get” it without actually understanding it than it is for them to get the same false positive from playing with a problem.

When it comes down to it, I just don’t see (yet?) a way for my students to really practice physics using videos, even ones that I make for them. When it comes to growing myelin, doing is much more efficient than watching (as I understand it). Maybe I’m just being stubborn. I’ll keep thinking about it. For now, though, I’m leaving it off my list.

* FYI: Mark and I share an office, which is why I feel so comfortable picking on him. I’m sure he will return the favor!
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About Kelly O'Shea

I teach high school kids physics at an independent day school in NYC. Less homework, more thinking. Follow @kellyoshea

Discussion

6 thoughts on “How to Practice Physics (By Really Trying)

  1. Kelly,
    Great ideas of how to use the same problem to get “new” practice. I’m betting that would work fairly well for reassessments too, as long as you were able to watch them do the the work. Thanks for the food for thought.

    Posted by Scott Thomas | July 4, 2011, 1:12 PM
  2. Ahh! Picking on your office-mate in the middle of a holiday! Foul!

    Ok, I’m over it… but you are forgetting that one of the deliberate practice techniques I mentioned in swimming involved watching video. That consists of viewing videos of themselves swimming, with Bill’s voice-over analyzing problems in their strokes. We also watch videos of Olympic swimmers… slow motion, underwater, above water, with expert coaching analysis. Neither of these techniques takes up much of a percentage of practice time, though. I just thought I’d point out that it isn’t zero percent… we think we get enough good out of it to do it, although no one would practice swimming by watching video every day! I feel the same way about video in physics.

    I agree that passively watching (even my excellent ;) ) videos will do precious little to help a student. I think the students who get some good out of them either don’t actually need much help (just a tiny reminder or hint) or watch them actively (trying to do what they see right after they see it). If a video can help a student slow down, ponder and practice, then it might help. I don’t see a way to guarantee that any particular video will do that for any given student, though.

    Posted by Mark Hammond | July 4, 2011, 5:20 PM
  3. Mark and Kelly,
    Building on your ideas—what if you had kids video themselves explaining problems—using something like a livescribe pen, and then narrated some feedback to them as they were working? This would seem to be very similar to how Mark describes using films of swimmers with narration from the coach…

    Posted by John Burk | July 4, 2011, 6:35 PM
    • Quick reply: Sounds like a huge time-suck with little payoff to me.

      More thoughtful reply: Swimming is a lot more repetitive than solving physics problems, so maybe seeing commentary on your technique over and over would be helpful… I do wonder often they rewatch old videos with commentary, though. I don’t really know what I’m talking about with the swimming videos, but it sounds like a one-time deal to get some extra feedback before the next practice, not to watch multiple times every day. Anyway, and more importantly, I don’t want them to get really good at solving one problem, which is what happens for most kids when they focus obsessively on solving one problem in the same way over and over (which is the only result of a video of the problem because it’s not like a choose-your-own-adventure-video, right?). Then when they get a slightly different problem, they fall apart because they had just memorized an algorithm for solving that one problem, they hadn’t really practiced the skills involved as skills. And they get really upset because they “worked really hard” on that problem and it’s “not fair” because I’m giving them something totally different and can’t I just give them something that looks like the one they practiced? That’s what they practiced! So I want them to change the problem, solve it backwards, use a different problem, and actually practice the skills. I just don’t see how a video could be good for this. I feel like we’re trying to find a use for video rather than having a need that video could fill. It seems really backwards to me. I’ve never thought, “Oh, you know what would make this happen more easily? If we had a video.” When I do, then I’ll get less stubborn.

      On a sidenote: I’ve definitely thought, “Oh, you know what would make this happen more easily? If we had [some graph paper, a pencil, a whiteboard, an eraser, a spring, the matter model, some sticky tape, a spring scale, the hover disc, a slinky, a motion sensor, the projectile launcher, an LOL diagram, a tuning fork, two tuning forks, a meter stick].” But so far, never a video.

      And one more thing: it is hard for the swimmers to see what they are doing while they are doing it (for obvious reasons), so commenting on a video afterward makes sense for that purpose. It is easy for students to see what they are doing while they are working a problem, so coaching them in real time makes more sense to me than coaching them in video afterwards.

      Posted by Kelly O'Shea | July 4, 2011, 6:49 PM
      • You completely nail why we use video in swimming. I’m not saying that the specific usages of video in swimming and academics are analogous. I was just pointing out that it was erroneous to say there was no video used in swimming. The use of video in swimming is more analogous to what we do everyday during small group work in class. We don’t need video for that (“Hey, let’s take a look at the video and see what you wrote on your whiteboard… oh wait.. it’s on the whiteboard.”) That is, in swimming we use video to provide quick feedback (and it would be quicker if we had a large screen on deck and a DVR… oh, we can dream).

        I totally agree that making a bunch of instructional videos would be a time-suck. That’s why you don’t see me creating a catalogue of such videos. What I was trying to point out is that I have occasionally found situations where I can save some time using a video. In fact, I do look at some situations and say to myself, “A video would work well here.” For instance, on summer homework when I find myself writing similar instructions and prompts for many students, when it would be easier if they could see something instead. “Tell me, I forget. Show me, I remember. Involved me, I understand.” (NCCL motto) Our summer homework does some telling and does some showing in order to get the students involved. And you can also show in a way that prompts the next step to involvement (I’m thinking of Derek Muller’s videos). But you are right, involvement is always the goal.

        So what I was trying to get across in my blog is that, to my surprise, a few students (very few!) actually used video (which I thought would just show them something to get them over some barrier) in a way that got them more involved than they had been. It actually shocked me that these few students got some deep practice out of a video, to tell the truth. But then, I can think of lectures that got me totally involved and active. I can think of reading that got me totally involved and active. I would be an unlearned basket case if I hadn’t, since these were the two main modes used by my teachers during high school and college.

        By the way, the main point of your post (different deep practice schemes) is great. It addresses the questions I’ve been pondering all year. These ideas involve things we’ve used, but putting it into writing is really helpful.

        Posted by Mark Hammond | July 5, 2011, 7:23 AM
    • Okay, obviously I’m the one who said on the survey that I would use short instructional videos in my classes when Frank started working for Sal Khan.

      Posted by Kelly O'Shea | July 4, 2011, 6:57 PM

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