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Archive for the ‘scaffolding’ Category

What do you mean, “relevant?”

22 Mar

Do you try to make your lessons relevant to your students and their lives?  Do you struggle to find ways your students will actually use your math in the future?  I suggest a reframe: make lessons relevant to your students by immersing them in mathematical situations during class.  Don’t worry too much if you can’t find something in their life outside of class.

My text book refers to bank accounts to make exponential equations relevant, and so does yours, probably.  Some problems with this example are obvious: my account is compounded monthly instead of continuously, I put money in and take money out at weird intervals, etc, so this math actually does not apply without modification.  Some problems are more subtle: you don’t need to know about exponential equations to pick a bank account, you just pick the one with the highest interest rate.  My students have very little money and differences in interest are on the order of pennies per year.  My students don’t have bank accounts.  My students don’t care about bank accounts.

The most subtle problem (that I’ve found, anyway) is that even students who do care about bank accounts aren’t opening bank accounts at the moment I am trying to teach them about exponential functions.  Even if the example is relevant to their outside life, when they are in my class they are not in their outside life.  The best I can do is “imagine you’re choosing a bank account” or maybe “find three bank accounts online.”  What I want is a student faced with a problem that he wants to solve during our class.

Give up on outside relevance in favor of inside relevance.  Pass out super balls.

This idea is from CPM’s Algebra 2: Connections.  Ask students, “how high will your ball bounce?”  They will have a mental crisis as they think of all the reasons this question is unanswerable in its current form.  Already they are thinking about a problem during my class.  Better yet, they are pretty fluent in bouncing already – they have bounced a lot of things in their day, you know?  They have some vocabulary to describe what’s going to happen, and a framework in which to place guesses.

You get the idea: it turns out that the height of bounce x follows a path almost exactly exponential, and you can ask students how high the second bounce will be, and how high the tenth bounce will be.  Please note that this has nothing to do with anything that “matters” in “real life.”  This activity makes exponential functions relevant by showing kids how exponential functions can improve their fluency about bouncing.  Exponential functions give them the power to, with absurd accuracy, guess how high the fifth bounce will be – and everyone likes that.  Increased fluency about reality is relevant to everyone.

So I’ve traded outside relevance for inside relevance, and the biggest difference is that I am teaching during the problem-solving process instead of before the problem-solving process.  The kids who learn about bank accounts won’t use that math until they are opening a bank account, and at that point they can’t get help from me or from classmates.  The kids who learn about bouncy balls use the math at the same time they are learning the math, and so their ideas are immediately challenged and reinforced by results.  It’s better!

 

Interesting questions aren’t enough without scaffolding.

16 Nov

For one thing, you might be wrong about interest levels.  Today I stretched a 10-minute conversation into a 40-minute bore-fest by failing to anticipate low interest levels.  I was not prepared to scaffold what I thought would be a self-directing conversation.

I started the class with a warmup of some pretty easy questions.  ”If a car moves at 50 mph for an hour, how far does it go?”  And also “for one minute, for one second, for 0.1 seconds?”  The students could solve these problems with little difficulty – they handled unit conversions like pros.  Then I asked, “how far does this car go?”

I wanted to give them a crisis, that old methods couldn’t solve.  I thought this would motivate at least the usual level of excitement in our class discussion, but the kids didn’t care.  Immediately, eyes started wandering around the room, and wrists came up to support bored heads.  Really?  But I was so sure this would be cool.  190 mph is pretty fast, guys!  And our old methods don’t work!  Cool!  Right!?

I prodded.  ”Can anyone think of any way to estimate how far this car went?”  I got a few answers: vaguely half-formed references to a physics class, maybe (vf-vi)/t, oh maybe that’s not right, I don’t know, you can’t figure it out, why would you want to figure this out?

At one point someone said it would be nice if we knew how long this took, so I switched to the video with the overlaid timer.  Attention spiked at this, but we spent almost 40 minutes struggling with this question, and attention faded again quickly.  My hope for the period was that we would come up with some version of numerical integration, or approximation by differentials, etc.  Something like “we can approximate how far the car went between seconds 5 and 15 by using an average speed.”  Our actual product was pretty good – the students eventually made a stab at the average velocity of the car over the whole 50-second period, and multiplied by 50 seconds, to find 1.4 miles.  But it took so long that we didn’t have time to refine or generalize the concept.  I could have made this lesson much better.

Ways to Improve

  1. Prior discussion of some tools to help us with this sort of problem.  I wanted to go from this problem to using differentials to approximate square roots, but that ordering might be backwards.
  2. When the students were just staring blankly, I should have asked, “Well, did the car go a thousand miles?”  They would have been able to see that the car did NOT go a thousand miles, and I could ask them how they knew.  There are any number of focusing questions in this vein that do not give away the answer or the process.
  3. I could have just asked, “how far did it go between the 5- and 6-second mark?”  From there the students would have an opportunity to generalize from a smaller problem to a bigger one.
  4. Video that includes terrain outside the vehicle would no doubt be much more impressive.
  5. Any others?  What intermediate steps could I interpose to lead my students to a numerical integration?  Please leave more ideas in the comments!

Looking back at the lesson, I’m a little appalled that I didn’t think of 2 and 3 during the lesson.  I was so worried about saying too much and allowing the students to get through without really processing anything, that I was paralyzed and led this boring class.  Ugh!  Have you ever had a class like this?

The Videos

 
 
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