Henri Picciotto's

Math Education Newsletter

February 2021

Staying at home, working at the computer — that was largely my life even before COVID. Put it another way: I have not been affected by the pandemic nearly as much as so many others: medical personnel, farmworkers, grocery store clerks, theater people, and of course teachers.

I've continued to support math education as best I can through my blog and website, and with occasional online workshops. (Should your department, school, or district be interested in one of my workshops, I am available!)

On March 11-12, I'll be participating in the Math Buffet, a 24-hour international online math event for kids, sponsored by the Julia Robinson Math Festival people. Read more about it at the end of this newsletter.


Blog Posts

Here are links to posts on my Math Education Blog that you might find interesting.
If you are so moved, you may comment on the posts, and/or subscribe to the blog.

Tiling (aka Tessellation)

This is a series of three blog posts.


In the first, I argue that tiling the plane (tessellation) is a legitimate topic in school mathematics: it provides an outlet for student creativity; it teaches mathematical habits of mind; and it is a great context for basic geometry (angles, parallels, polygons, ...).

In the second post, I explain how tilings can be used to introduce rigid motions and to suggest some basic theorems in transformational geometry.

The third post is written by John Golden. It is a step-by-step GeoGebra tutorial on how to "Escherize" what starts as a simple geometric tiling.

(See also the Tiling home page on

Transformational Geometry for Teachers

This is essentially a syllabus on geometric transformations for teachers and future teachers. I outline the content teachers need to know, and how to prioritize those topics. I end with a discussion of issues that came up in conversation with fellow math educators. Read it here.

Teacher Eclecticism

In 2016, when someone complained I lacked a pedagogical framework, I agreed, and advocated eclecticism. In the real world of the classroom, teachers cannot limit themselves to a single philosophy of education, whether based on tradition, research, or the latest fad. This generated a strong response on Twitter: teachers seemed to love it, but non-teacher math educators took issue with it. This led to a couple more posts: Math Education Research, and Fads and Memes.

New on my website.



It is sad that symmetry is very much under-emphasized in the Common Core State Standards. It is a crucial topic in mathematics, and offers excellent opportunities for student creativity and for connections to art and culture. I now have a Symmetry home page which links to new and old materials.

Two new units:
- ten lessons for grades 1-6, suitable for the classroom or for a math circle, originally created for the Museum of Math's summer program;
- and a dozen activities for middle school or high school, suitable for either in-person or remote instruction.

The page also links to existing materials throughout the site: activities in Geometry Labs; a set of paper-scissors puzzles; a spirograph simulation; and more!

Navigating the Site

I can't resist quoting math educator John Golden's comment about "Henriā€™s site is really the most comprehensive site any one person has made to support math teachers, while also being of utmost quality."

Indeed, for something created by one person, the site is huge. To find things, you can search, or use one of five site maps, each organized in a different way.
- The site's front page has images linking to many launch pages within the site.
- The annotated map links to a selection of pages, and offers a brief description of each. It is organized into eight top-level categories.
- There is a site map organized by grade level.
- The comprehensive map attempts to list every single page on the site in alphabetical order.
- I also compiled an alphabetical directory of directories.

The latter is the most recent addition. If the topic you have in mind happens to be on that list, it is probably the fastest way to get there.

Finally, there is a navigation bar at the top and bottom of almost every page. Hovering your pointer over its text and icons will provide you with many useful navigational links. Just click on those.

Improvements, Tweaks, and Updates

Maintaining a site this big involves constant updates. Here is a very partial list of pages I tweaked in the past few months, some of them more substantially than others.
Virtual Tangrams
Virtual Pentominoes
Virtual Lab Gear
Geometry Labs
Geometric Puzzles
Polyomino Lessons


On March 11-12, I'll participate in Math Buffet, an online international math festival for kids 10 and older. It will start on Thursday, March 11 at 4pm (Pacific time) and run for 24 hours. The program includes a wide variety of events and a wide variety of presenters (including elementary math guru Marilyn Burns, Math Pickle's Gordon Hamilton, mathematical sculptor George Hart, puzzle creator Scott Kim, dots exploder James Tanton, and many others). I will lead some puzzle activities.

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