Liu Hui was a 3rd century Chinese mathematician. I first stumbled upon him when I saw puzzles based on dissection proofs of the Pythagorean Theorem (Shang Gao Theorem (商高定理)) at ICME11 in 2004. Recently I’ve been exploring the trisection of a cube, so I could give students a way to discover the formula for...
Read more →It’s a tricky thing, trying to profit (or at least break even) from an idea born in the classroom. But that’s what I’m trying to do. It is a challenge because my professional life overlaps with my new business, and I don’t want to be seen as one who takes advantage of those overlaps....
Read more →How it might work – in a nutshell (maybe a coconut) Working as a class, students will construct the 50 pyramids that make up the five Platonic Solids. These pyramids all have a height of 5 units, and each one has a polygon that is a face of one of the solids as its...
Read more →The CCSS call for lessons on conic sections – after many schools have stopped teaching them, at least in non-honors classes. So, I wanted a way to show students how these slices of cones are defined and where the parts of the equations come from. I got busy in GeoGebra, spending a weekend making...
Read more →I came across this NPR article by Robert Krulwich, called “What Is It About Bees And Hexagons?,” and I got totally sucked in to the comment thread. The more I read, the cooler it seemed, and the more I wanted to build these things and teach my kids about them. Each cell starts out looking something...
Read more →I have posted a bunch of lessons that have an opening prompt, but little direction. Linked to those prompts are scaffolded lessons. The passwords are listed parenthetically on the main menu pages (e.g. Algebra21). This strategy allows teachers to control when (if) students get the scaffolded versions.
Read more →