Last night I was looking through *Count Like and Egyptian * by David Reimer looking for a new project and stumbled on an idea about square pyramids that we’ve touched on before. Seemed like a nice review project.

Prior similar projects to this one are:

A neat geometry project inspired by a James Tanton / James Key tweet

Revisiting an old James Tanton / James Key Pyramid project

and

Octahedrons, Tetrahedrons, and the Pyramid Puzzle

Some of our old projects from Count Like and Egyptian are here:

Going through *Count Like an Egyptian* with the Boys

I started today’s project introducing the pyramid topic from the book and having the boys play with some small pyramid pieces we’d 3D printed for previous projects.

They boys were able to use the pieces to see that the volume of the square pyramid we had was 1/6th of the volume of a cube whose square sides were the same size as the base of our pyramid.

For the next part of the project I wanted the boys to build a cube made out of these 6 square pyramids. We started by building the small pyramid shapes and talking about how you could use them to form a cube:

After building the smaller pieces the boys worked for about 10 minutes to build the cube with the square pyramids inside. We talked about the various properties of that cube here:

Finally, after the brief discussion of volume formulas in the last video, we returned to the whiteboard to have a (slightly) longer discussion. The point here wasn’t to derive the formula but rather to show that at least the two sets of pyramids we studied in this project had volumes that we could find using the formula.

So, a nice little review project which hopefully helped some of the ideas from previous projects sink in a little more. I like working through these 3d geometry project with the boys.

AND, after we were done our little Zometool pyramid captured BB-8 ðŸ™‚