Convex Tangram Polygons

If you’re a regular reader of this blog, or visitor to my website, you probably know of my long-standing interest in geometric puzzles. Among those, tangrams are probably the most well-known and widely available. Thus I included them in Geometry Labs (free download) where they are the subject of Section 2, and Lab 10.6. In this… Continue reading Convex Tangram Polygons

Making a GeoGebra Slide Show

I’m a long-time user of interactive geometry software, of which the dominant instance these days is GeoGebra. Here are some ways it’s enhanced my teaching over the years. Most obviously, it provides an environment for students to explore geometry and geometric construction. I’ve written much about it on this blog, and shared some curriculum on… Continue reading Making a GeoGebra Slide Show

Asilomar report, 2021

I attended the California Math Council North’s conference in Asilomar last weekend. Because of Covid, it was a dramatically smaller conference than usual. As a consequence, there were fewer sessions to choose from, and probably a smaller turnout for many of them. Here is my nearly annual report. Python Turtle Ned Diamond presented the Python… Continue reading Asilomar report, 2021

Seeing is Believing?

“Proofs Without Words” are proofs based on a visual representation of a theorem which provides a convincing argument about its validity without the need for any accompanying text. The genre has been much enriched by the increased availability of computer animation. This is of course relevant to math education: many of the concepts we teach can be illustrated visually, including with… Continue reading Seeing is Believing?

Wallpaper Symmetry Part 2

This post is a continuation of Wallpaper Symmetry Part 1, which you should read first. Both posts are companions to the Wallpapers Catalog on my website. --------------------------------------------------------------------- A long time ago, in my twenties, I attended a lecture about the mathematics of wallpaper designs. The presenter gave an overview of the entire proof that there are only… Continue reading Wallpaper Symmetry Part 2

Asilomar Report: Conic Sections

As my retirement starts to kick in, I no longer attend conferences — except for one: the annual meeting of the California Math Council (Northern Section.) Once again, I had a great day at Asilomar, a beautiful spot near Monterey, right on the Pacific Ocean. Here is my annual report. Conic Sections Figuring out an approach to… Continue reading Asilomar Report: Conic Sections