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

User-Controlled GeoGebra Animation

Here is an animation I created in GeoGebra: As far as I can tell, WordPress only shows you the animation once, when you open this post. You can find the actual .ggb file, and an interactive applet in your browser here. (Links to related transformations applets are on this page.) The idea was to illustrate reflection in… Continue reading User-Controlled GeoGebra Animation

Minimum Polyomino Cover

When I taught elementary school (1971-1981 or so) I had more time for “enrichment”, which for me meant excursions off the beaten curricular path, especially into the world of recreational math. As a result, my first publications were largely about geometric puzzles. (Those books were assembled a few years later. More info about my books.) Anyway, one… Continue reading Minimum Polyomino Cover

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

Teaching the Distributive Property

A guest post by Rachel Chou I have been a classroom mathematics teacher for 20 years.  I have heard students use the phrase “the distributive property” more times than I can count.  Many of them misunderstand what “the distributive property” even is.  But maybe I think that because I don’t really know what “the distributive property”… Continue reading Teaching the Distributive Property

Freakonomics Radio on Math Curriculum

Every now and then, an academic decides they’re qualified to fundamentally rethink math education, and to share their brilliant solution with the world. That is already problematic when the academic is a mathematician or a math education researcher, but it is even worse when it is someone whose only connection to K-12 math education is that… Continue reading Freakonomics Radio on Math Curriculum