Hello, reader! If you intend to post a link to this blog on Twitter, be aware that for utterly mysterious reasons, Twitter thinks this blog is spam, and will prevent you from linking to it. Here's a workaround: change the .com in the address to .ca. I call it the "Maple Leaf Loophole." And thanks for sharing!

Tuesday, December 21, 2010

Log Laws

(Update! After this post and all the comments, I modified the student handout to include a little proof section after each part. You can find it here.)

Hate em. Can't teach em. Kids are confused by em. Kids never, ever remember em when they need em.

This year, like last year, we took the definition of a logarithm and knocked it out of the park. We were all feeling good after Day 1. "This is pretty easy." "Why does everyone say logs are such a big deal." Etc, etc. Right on, kids. Right on.

Then on Day 2, boom, the fit hits the shan. We left class looking dazed, bewildered, scared. Well this is my third year teaching Algebra 2 and I decided that This Would Not Stand. (I guess I only have one good, new lesson per unit in me every year. But like ten years from now, LOOK OUT.) So we re-did Day 2, differently, and even though losing a day in Algebra 2 gives me an ulcer, it was worth it.

What was I doing that was so awful? This:

Barfity barf barf. It's like I forgot how to teach math. I think I thought this topic was sort of hopeless and useless so I gave up on it for a little bit.

This is what we did that was better. Go get it here if you like. (Note: It uses the mathtype plugin for Word.)

Tuesday, December 14, 2010

Review and Practice: Add Em Up

This worked really nice as a practice activity today, by my criteria of : the kids talk to each other, have ways to figure out if they're correct, and have ways to find their mistakes if they're not. I like when I can spend my time helping kids who need it and asking and answering meaningful questions, and don't have to hear "Is this right?" over and over.

The students got in groups of four, and each group got a total of 16 problems. Four pieces of paper with four problems each. The papers were different colors.

The students completed one problem on each page. So they all worked on one, rotated papers, worked the next one, etc. These guys even coordinated their calculators.

The paper color corresponded to the difficulty of the problems, which I let them know.

When all four problems were complete on a page, they added up their four answers. I posted the sums on colored index cards.

So if they check their sum and it's correct, great. But the best dialog started if it wasn't correct. Because first, they had to figure out which out of the four answers was wrong. And is it smart to start over and re-do the problem? Not in this case, since they were solving equations. It made much more sense to plug the answers in and see which one didn't work. Then they could start error-checking their work, which is great practice in itself.

The topic was solving exponential equations by changing the base, though this could work for anything. The document with the problems is available here. Enjoy!