# Geometry Labs + Which One Doesn’t Belong

I love Henri Picciotto’s Geometry Labs text. I was preparing my geometry class for his inscribed angles activity, and saw this:

Thanks to the Which One Doesn’t Belong people (and Christopher’s lovely book), I’m no longer able to look at sets of four things. It’s ruined me. I’m always deciding which of them is the odd one out.

Since there are subtle differences between the inscribed angle cases, I decided to cover up the words and ask my students which of the four diagrams was the weird one.

This drew attention to the location of the centers, the location of radii, and the presence of isosceles/scalene triangles. (I know it’s May, but any chance to get kids to practice using this vocabulary is time well spent.)

This week in 4th Grade I’ve also been using Geometry Labs‘s chapter on tilings. (Sort of a random topic, but random topics are fun. Plus, I need to figure out where we stand on multiplication/division before one last push in our last weeks together.)

There I was, trying to figure out how to attune kids to the subtle classification differences between these two square tilings…

…and while, admittedly, I clearly had “Which One Doesn’t Belong” on my mind, it seemed a pretty good fit for my need here too. I took out some pattern blocks and snapped a picture:

There were lots of interesting aspects of this discussion, though my favorite had to do with whether the top-left and bottom-right tilings were different. I forget if we’ve talked about congruence yet in this class, but there were a lot of good ideas about whether tilting the tessellation made it a different tiling.

Not much else to share here, but I guess I’d say that I do this a lot. I don’t rewrite texts or worksheets or whatever very often. More often I add little activities before or after, to make sure kids can understand the activity, or to react to their thinking. That’s good for me (because I don’t have time to remake everything) and good for kids too (I write crappy curriculum).