(To search from previous posts on this topic, use the Search box on the right.) I suspect that by far the most common introduction to geometric construction in US classrooms is a presentation by the teacher (or textbook) on various compass and straightedge construction techniques. “This is how you construct a perpendicular bisector. This is… Continue reading More on Geometric Construction →

If you’ve been reading my blog for a while, you know that I’m a big fan of geometric construction. I have written about it here more than once, and my Web site includes quite a bit of curriculum involving construction. See the end of the post for additional links. I have many reasons for this… Continue reading Geometric Construction for Middle School →

Readers of this blog probably realize that I’m very much into geometric construction. This is in part related to my general interest in puzzles, in and out of the classroom. (In my other life, I construct cryptic crosswords.) My first math education publications were books of geometric puzzles for grades K-10. My pentomino puzzle books stayed… Continue reading Geometric Construction, continued →

In the days preceding a recent lunar eclipse, my daughter saw an illustration that seemed to show that the Moon’s diameter was just about equal to the width of the penumbra. She conjectured that if that were true, it may be because of the fact that the apparent diameter of the Moon (as seen from… Continue reading Astronomy and Geometric Construction →

5 October 2019: Along with Kim Seashore and perhaps others, I will be a presenter at Lessons from Lew, a free professional development session. We will share Lew Douglas’s lessons on trigonometry, the golden ratio, symmetric polygons, and more. 11:00 to 12:15, at Longfellow Middle School in Berkeley. Register here. Links to an expanded version… Continue reading News →

In my last post, I shared some generalities about puzzle creation. Today, I will zero in on the specifics of creating puzzles for the mathematics classroom. I will do this by way of analyzing some examples. Multiple Paths A characteristic of all classrooms is that they are constituted of students whose backgrounds and talents vary… Continue reading Puzzles for the Classroom →

I’ve really enjoyed solving the puzzles in Euclidea, a brilliantly designed app for iOS and Android. The basic format is “given this, construct that”. You start with just two tools: a straightedge and a slack compass (i.e. a compass that does not remember the radius it was last set to). As you find useful and… Continue reading Stumped by Euclidea →

I will offer two workshops this summer (2017), at the Head-Royce School in Oakland, CA. Sign up for either or both! June 26-27: Hands-On Geometry (grades 6-10) June 28-30: Transformational Geometry (grades 8-11) If the times or locations don’t work for you, I can offer a workshop for your school or district. Contact me directly.… Continue reading Geometry Boot Camp! →

I only attended a few sessions at NCTM-Boston, because I spent a fair amount of time promoting the Lab Gear. I already posted my report on Geoff Krall’s strategies to improve the problems we find in standard textbooks. In this post, I’ll go over some of the other worthwhile ideas I came across. – Scott… Continue reading NCTM wrap-up →

As you may remember from my previous posts on this subject, I have been thinking a lot about the Common Core approach to secondary-school geometry, specifically the logical switcheroo that makes triangle congruence and similarity a consequence of assumptions about geometric transformations, rather than the other way around. To support this change, I have started… Continue reading Triangle Similarity Update →