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Dylan Kane's avatar

I love this idea! Here's my my mind went: how does this apply to a few generalizations I teach? What I'm thinking is that there is a relationship between the complexity of the specifics and the complexity of the generalizations.

Example one, unit rates. A really helpful generalization in 7th grade math is "find the unit rate and use that to solve the problem." Students often have a pretty good intuition for these. "You go 10 miles in 2 hours, how many miles do you go in an hour?" is a problem lots of kids just know how to solve or can solve with some pretty minimal nudging. Same with "you are biking at a speed of 15 miles per hour, how far will you go in 3 hours?" The generalization is more complex -- unit rates are hard to explain, though with enough examples they start to make sense. So you can do lots of small specific examples, and then try to climb that ladder to generalization. Specifics are simple, generalization is complex.

Example two, two-step equations. The generalization here is something about inverse operations or undoing things or doing the same thing to both sides. But the specifics are hard! It is hard to understand how to solve 3x+2=14. I love tape diagrams as does the IM curriculum so we spend a lot of time on those. Here the generalization is still complex but so are the specifics. This generalization is always tough for me, we spend so much mental energy on the specifics it feels tough to really generalize. I still think your framework is helpful here! Just different, because of the complexity of those specific cases. Specifics are complex, generalization is complex.

Example three, complementary angles. Here I think both the specifics and the generalization are pretty simple, and not that different from each other. This topic relies on some prior knowledge and really benefits from students who have good intuition for angle size in general. But we do some specific examples and the generalization is mostly just recognizing right angles in places where they're not obvious and applying complementary angles in problems that include other stuff as well. Specifics are simple, generalization is simple.

All of those are my subjective judgments based on my experience. Maybe I'm trying to shoehorn this stuff into a box it doesn't fit into. (Also, are there topics where the specifics are complex and the generalization is simple?) But when I read this post I was thinking "whoa this applies so well to some things I teach but not to other things, why is that?" and this is what I came up with as a first stab at trying to understand.

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Kevin Hall's avatar

How do you handle the tension between the implications of this framework and the desire to validate students’ own approaches, when those approaches may be less “principled”?

When I ask an open-ended question, a few kids solve the problem in the simplest “principled” way, but most will hack their way through using common sense or something. It feels disrespectful to highlight the “principled group’s work and then try to demonstrate that the other groups were using a disguised (less-efficient) version of principled method. Doing so creates a hierarchy of methods and communicates, “you got the answer, BUT…” to the “common-sense groups.

How do you recommend handling this?

Maybe it’s okay to just have straight-up conversations about efficiency, and maybe I avoid those too much.

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