Twitter is amazing. Two nights ago I watched the PBS documentary on origami, Between the Folds. Yesterday morning when I got to my office I made the following post on Twitter: In the next 12 hours I was flooded with suggestions, comments, and links. Here are some of the book titles and links that people sent…

## Kindergarten mathematics

This is a call for help. My son’s kindergarten teacher has invited parents to come in and talk about their careers. I’d like to go in and talk about math. I’d like to have some interactive hands-on mathematics activities for the kids to do. I also want them to be activities outside the typical kindergarten…

## Folding a golden rectangle

Recently I wrote about the mathematics of cutting and folding paper and about the golden ratio, . Here’s a video that brings these two ideas together. We see how to create a golden rectangle (a rectangle for which the ratio of the sides is ) by folding a piece of paper. [via Anthony Brand’s maths…

## Cutting and folding paper

Inspired by Chaim Goodman-Strauss’s recent video about symmetries, paper snowflakes, and paper dolls, I decided to post a few other paper-related videos. First is a video showing some cutting tricks for a Möbius strip. I show this to my topology class, then have them play around with Möbius strips—twisting them various numbers of times and…