Transformational Geometry for Teachers

I taught geometry for decades, starting in the 1980’s, and loved it. I’m reasonably good at manipulating algebraic symbols, but I don’t especially enjoy it. In contrast, I am happy to spend plenty of time on visual puzzles, and I am enthusiastic about sharing that passion with colleagues and with students. Early in my high… Continue reading Transformational Geometry for Teachers

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

Remembering Lew Douglas

(Post updated on 19 Jan 2020.) The Bay Area Math Project and the Alameda Contra Costa County Math Educators presented Lessons from Lew, a professional development session in memory of Lew Douglas,  a leading Bay Area math educator who passed away in April. Lew delighted in math and developed lessons to allow others to share in that wonder. We… Continue reading Remembering Lew Douglas

Learning from Teaching (cont.)

For the second time this summer, I taught a version of my Visual Algebra workshop, this time as part of a summer institute at the Atrium School near Boston. (Earlier in the summer, I did this at Synapse School, in Silicon Valley, and wrote about it here.) Once again, I walked away from the workshop… Continue reading Learning from Teaching (cont.)

Asilomar Notes: Tech

It is widely agreed among its attendees that the Asilomar meeting of the California Math Council is the best math teacher conference anywhere. Certainly, the setting is beautiful. Over the decades, I have attended some great talks there, and this year was no exception. I will post some notes and reactions here, starting with two tech-oriented talks I… Continue reading Asilomar Notes: Tech

April Travels, May Webinar, Summer Workshops

I'll be traveling a lot this month. Here's the plan, should you want to say hello.New York City April 5, 4:30pm: I will present Geometric Puzzles at the Museum of Math Teachers’ Circle. Geometric puzzles are accessible to solvers of all ages, but they can also challenge even the most tenacious of solvers.  Join math education author… Continue reading April Travels, May Webinar, Summer Workshops


In my last post, I offered guidelines for sequencing math curriculum. The response I got on Twitter (and in one comment to the post) was quite positive. However, one point I made triggered some disagreement:Start with definitions? No! Most students find it difficult to understand a definition for something they have no experience with. It is more effective to start… Continue reading Vocabulary