In my last post, I discussed Every Minute Counts, a book that influenced me early in my career as a high school teacher in the 1980’s. It was mostly useful because of David R. Johnson’s suggestions on how to run a class discussion, and his insistence that the teacher needs to hear from every student, not just the… Continue reading Geometry: A Guided Inquiry

# Tag: Geometry

## In Defense of Geometry: Part II

In my last post, I complained about the shrinkage of geometry, a decades-long trend in US math education. Some of the reasons I suggested for this state of affairs is the offering of a substantial amount of algebra to a much broader population, the growth of calculus as a high school subject, and the increasing place given to… Continue reading In Defense of Geometry: Part II

## In Defense of Geometry: Part I

In 2016, I wrote In Defense of Algebra 2, a blog post addressed to math educators who do not see that Algebra 2 can be engaging and worth teaching to all students. In this post and the next, I defend geometry. This is a different sort of argument. Algebra 2 has been offered to more and… Continue reading In Defense of Geometry: Part I

## 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

## Geometric Puzzles at Asilomar

I'll be presenting a session on Geometric Puzzles at the Asilomar meeting of the California Math Council. (Saturday, Dec 2, Sanderling, 1:30pm The printed program says I'm in the middle school, but that is not correct. The app has the location right.). I will include material that I believe is relevant to teachers from kindergarten… Continue reading Geometric Puzzles at Asilomar

## Puzzles for the Classroom

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 PathsA characteristic of all classrooms is that they are constituted of students whose backgrounds and talents vary widely. … Continue reading Puzzles for the Classroom

## Scissors Congruence!

I attended the San Francisco Math Teachers' Circle last weekend. It was facilitated by Paul Zeitz. The topic: showing two polygons have equal area by cutting one into pieces, and rearranging them to cover the other one with no gaps or overlaps.The assumption was that the area of a rectangle is length times width. The… Continue reading Scissors Congruence!

## Stumped by Euclidea

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

## Transformational Proof

Prior to the publication of the Common Core State Standards for Math (CCSSM), transformational geometry was rarely seen in geometry courses. It certainly was missing from the one I taught. Still, I have always been interested in this topic, and it provided the backbone of my "Geometry 2" class, a post-Algebra 2 elective which I… Continue reading Transformational Proof

## More on Geometric Construction

(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