# NCTM, day 2

The second day was a disappointment. Of the four talks I went to, three of them were bad. If they were a smell, I would be passed out. So bad. I actually felt angered by two of them, because the description was so fascinating that I felt betrayed. Talks in sheeps clothing.

I feel bad listing the three terrible talks, so instead I thought I’d at least point to the one good talk:

#201: Linear Functions: Much More than y=mx+b

The major thesis of this talk was that we might want to invert our traditional way of teaching linear functions. We tend to teach:

1. $y=3x+4$
2. make  table of x-y values
3. plot
4. connect the points. oh my gosh! a line!

But students find the equation $y=3x+4$ to be the abstract part. The numbers and working with them is the easy part. So the speaker provided some ways to say let’s END with the equation and have it make sense to the kids, rather than START with the equation.

What was nice is that he started with some easy problems — that I couldn’t use in my classes — but then went to more advanced and more interesting problems — including one that would be great for an independent research project for a kid, and one that just blew my mind relating Pick’s Theorem to… systems of equations. Seriously.

But what was great is that he focused on student learning, and eschewed ed jargon and talked about why he made his choices for each lesson, and what his students got out of it. It was sweetness.

UPDATE: Commenter “m” below has prompted me to flesh things out a bit more. The easy part is with Pick’s Theorem… the speakers said he stole his connection to systems of equations from somewhere else… I suspect here! (He also showed a second way to derive Pick’s Theorem, which I am too lazy to do here. I remember first learning about this theorem in high school and spending days trying to prove it. I did eventually prove it and proudly showed my writeup to my math teacher.)

As for motivating simple linear functions, he basically had students engage in pattern recognition and play around with numbers.

White blocks in the first picture? The second picture? The third picture? What about the 5th picture? The 27th picture? He also talked about relating the blocks to tables to graphs really explicitly, as well as making explicit the connection between the “slope” (I put that in quotations because the speaker hates the term slope – he thinks it obfuscates) and the pattern, and the “y-intercept” and the pattern. His thesis was actualized: being explicit and very visual, and having students start with numbers and then come up with the equation out of these numbers provided a more natural and more deep way of motivating linear functions.