*Pythagoras Plugged In*by Dan Bennett. Dan's book contains 18 visual, interactive proofs of the Pythagorean Theorem. And there are more:

*The Pythagorean …*

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If there were an award for 'Mathematical Theorem Most Amenable to a Visual Proof,' the Pythagorean Theorem would surely win. The title of this post is a nod to the Sketchpad activity module *Pythagoras Plugged In *by Dan Bennett. Dan's book contains 18 visual, interactive proofs of the Pythagorean Theorem. And there are more: *The Pythagorean … **Continue Reading ›› *

I began this post on Friday night in Hamburg Germany, near the end of ICME, the quadrennial international math-education conference that's been both exhilarating and exhausting. I’m now finishing it on the airplane headed back home.
As interesting as many of the presentations have been, they've also been … Continue Reading ››

News alert! Scott and I wrote the cover story, Connecting Functions in Geometry and Algebra, in this month's *Mathematics Teacher.* You can read the article in print, but better yet, go to the free online version. This is the first time *Mathematics Teacher* has incorporated live dynamic-mathematics figures into its online offerings, allowing readers to manipulate the mathematical … Continue Reading ››

What does dilation feel like?
I recently had the opportunity to work with a group of students who were testing activities that treat geometric transformations as functions (what I call *geometric functions*). I got lots of good ideas for improving the activities not only by watching the students, but also but also from their suggestions and the … Continue Reading ››

In years past, my colleagues and I at Key Curriculum conducted Sketchpad professional development workshops for teachers. One of our favorite activities challenged participants to construct a rhombus in as many different ways as possible. This assignment invariably led to great discussions because there are a multitude of ways to build a rhombus, and each method highlights its … Continue Reading ››

When the Web Sketchpad team created the interface for tools, there were lots of design decisions to be made. We made the best choices we could at the time, but after months of daily use, it became clear that at least one aspect of tool functionality needed some rethinking.
In the original design of tools (which you can … Continue Reading ››

In a prior blog post, I described the pins-and-string approach to drawing an ellipse: Press two pins into a corkboard, place a loop of string around the pins, pull the string tight with a pencil, and trace the pencil tip's path as you pull the pencil around the taut string. Guaranteeing that the traced … Continue Reading ››

Did you know that aside from being a source of news, *The New York Times* is also the place to get your weekly fix of mathematics? Their online Numberplay column features some very clever math puzzles. Last year, in fact, our blog featured a Numberplay puzzle about a flying squirrel-frog from former Key Curriculum … Continue Reading ››

With Web Sketchpad, it's easy to craft tools that are tailor made for the task at hand. I was reminded of this flexibility several weeks ago when creating an interactive model for the elementary curriculum *Everyday Mathematics*.
My goal was to design a lesson focusing on the triangle area formula, *A* = *bh*/2. … Continue Reading ››