My class ends. I erase the board, tuck the unused worksheets on top of the folders and head out into the hallway when I see Benjamin. He has not been to class once, so there is no way I can’t go call him out on it. “You know, the reason I’m trying new material is because you signed up for the class.” Benjamin was in my class last cycle, and when he signed up I told him I initial told him he couldn’t take it because I had already taken this course. Then I caved. Both because he’s awesome to have in class, and because I like coming up with new stuff. “Why not just repeat the class from 2 cycles ago…” Benjamin replied “it’d be easier for the both of us.” What Ben is saying there is that today’s class was a struggle. You know it’s bad when even the kid who hasn’t even been there for two weeks can see how bad it is.

So I had an idea for a lesson. This lesson would fit right in with the unit where we finish talking about average median mode and start talking about standard deviation. In the past I have kids just do a huge mega table to understand the calculation side of it. What I don’t do is get the students to understand why such a calculation is important in the first place. So today I decided to make the new lesson. I thought that this lesson could involve the data that the kids generated in Friday’s circle, some practice with calculating the average, and the idea of “reliability.”

What I had them do was look at some bar graphs of the data from the last class. They could look at the bar graph and think about why the graphs show different ‘spreads.’ These bar graphs could then be used to calculate the average by looking at the values. They can then take that average and look at it in the context of the rest of the values on the graph and be able to make a statement about which graphs show the most clustering around the mean. I figured students would come up with their own ideas of which ones are clustering around, and then say stuff like “Graph A has the smallest range, so the numbers might be close to the mean” or “Graph D has most of the responses as one value, so that one is really close to the mean.” This would all lead to a magical debate, after which the class would realize that we need an approach to look at these data sets in order to figure this out. Then I would say “Well that’s why we have the standard deviation!!!” The kids would cheer, and high five each other, then I would get into the powerpoint.