# What a Difference 12 Kids Make

from map.mathshell.org

We’ve entered Spring Trimester and the volatile Minnesota weather is cooperating thus far.  If there’s a silver lining to last year’s Spring suckfest, the lack of warmer weather put off the end-of-the-year slide until closer to May.  I’m not sure we’ll have the same luxury this year.

I teach the same level of Algebra 2 that I did last year but my class sizes are a more manageable 22-24 rather than the monstrosity of 36 I had last year.  I know class size isn’t high on Hattie’s list of influences on student achievement, but providing formative evaluation (something VERY influential, according to Hattie) is much more doable with 20-something rather than 30+.

I’ve left the desks in pods because I’m convinced students interact and collaborate mathematically more often when they have multiple classmates within conversation distance.  I want to switch their groups periodically, if only I could get them to sit in their assigned seat!

One of my go-to resources is the Mathematics Assessment Project. Their lessons are robust, and provide good opportunities for students to have great conversations around the mathematics.  This lesson on investments is no exception.  The main activity is a card sort where students match a principal and interest rate of an investment with a formula, graph, table, and description.  But the everything from the pre-assessment to the closing slide makes students think and share.

Here are the openers of the main lesson:

from map.mathshell.org

from map.mathshell.org

My assumption, not being familiar with this group of kids, was that they’d go right for the obvious – Investment 3 is the odd one out because it has a 10% interest rate and the others have a 5% interest rate.  I underestimated them.  They came up with very creative, thoughtful reasons why each investment could be considered the odd one out.  I really like these questions because all three can be correct, and students have an opportunity to defend multiple answers.

The card sort was also spectacular.  I was able to have great conversations with each group about their thinking. (Yes, that’s much easier to do with 24 rather than 36).  What a difference 12 kids makes.  There is so much to this lesson to love.  If you have a unit on exponential functions, give it a try.  I’d love to hear how it went in your classroom.