Finding the shape that results from cutting a three-dimensional shape is a fun topic. Students really enjoy this topic. When you look for ideas for teaching this topic, you’ll inevitably find an introductory activity using play-doh. Students make the 3-D shapes out of play-doh and then cut them with a string of some sort. But there’s other ways to help students see and understand this topic, so I’m sharing 12 *other* activities today (but you can see some different versions of this play-doh activity here and here). [Read more…] about 12 Activities to Practice Cross Sections of 3D Shapes Like a Ninja

# geometry

## 11 Triangle Inequality Theorem Activities That Rock

The triangle inequality theorem is not one of the most glamorous topics in middle school math. It seems to get swept under the rug and no one talks a lot about it. Like most geometry concepts, this topic has a proof that can be learned through discovery. It’s pretty cool when students realize that they can actually figure out if 3 given lines will make a triangle. I love teaching this concept to 7th graders, and I like that it’s not super complicated. Most of my students can get this idea pretty quickly and they enjoy it. I’m excited to share with you 11 activities that will help students get, and remember, the triangle inequality theorem. [Read more…] about 11 Triangle Inequality Theorem Activities That Rock

## Teaching Effects of Transformations through Matching

The past two weeks have been dedicated to the study of the effects of transformations: translations, rotations, dilations and reflections of geometric figures on a coordinate plane. With this unit, I wanted to make sure students got lots of chances to talk about what is happening in mathematical terms. One of my favorite things we did in teaching transformations was to use match and paste activities. We actually used them TWICE in this unit. I can’t wait to show you just what we did and how it helped them OWN transformations. [Read more…] about Teaching Effects of Transformations through Matching