Day 85: Desmos + Grocery Lines

In Algebra, I gave students the option of using Desmos or a graphing calculator to find lines of best fit. I went over examples of both then dove into Dan’s Grocery Line activity.


I started by asking students which line they would pick, a little over half in each period said the left. I gave them about half of the data Dan provided (I did this last year also and there were some issues with data overload, but that was by hand) and let them loose.

Something interesting happened.

Most of my students set their cellphones aside and used graphing calculators. I am not sure why (I will report back tomorrow). My prediction is we have had quite a bit of practice creating scatter plots on them and students are more comfortable with calculators.

We talked about what the slope, intercept, and r-value meant, and also possible reasons why data is so inconsistent. They were hooked on this after this picture!


Day 84: Regression

Today was chaos. Algebra started finding linear regressions on graphing calculators. I have a set of 15 (identical?) calculators, however half of them have an out of date operating system. This baffles me because they all were shipped and arrived at the same time. So when we started imputing commands to find regressions different menus popped up.

I am extremely thankful for the #MTBoS responseĀ on Desmos having a regression tool, we are going over that tomorrow on cellphones and iPads. I am not sure how to tackle the fact that all students don’t have smartphones with Desmos capability. The computer labs are booked and it feels almost unfair to ask students to find the line of best fit on calculators when Desmos is so much easier.

Any ideas?