## Welcome! This is a bonus section.

I recently retired from teaching at Eleanor Roosevelt Community Learning Center, a charter school working with homeschool families. The most popular course I taught there I called “Math Explorations” (for younger students) and explained it as “Stuff that doesn’t look like math.” More recently I spent a few months as a volunteer in the Schoolhouse Teacher program, doing an online column that looks somewhat like Math Explorations, except it is for high school students. A part of each of my “lessons” was a series of videos on some topic, going beyond what is taught in regular school classes. Hopefully the videos and other material collected here will inspire you to think mathematically about the world we live in.

## Schoolhouse Teacher Videos

I have my Schoolhouse Teacher Videos in a playlist on the YouTube Math Without Borders channel called “Lessons of Interest on Assorted Topics”. There are quite a few videos, so rather than embedding them all here, see them on YouTube.

## Here are some of my other math videos:

### Solving a Maze

**The Pi Movie**

(See also the series of videos on Pi in the Schoolhouse Teacher videos)

### Introduction to the Pythagorean Theorem

### The Joys of RPN

(Make Your Calculator an Extension of your Brain)

### Multiplying Positive and Negative Numbers

### How to Subtract Without Ever Having to Borrow

### Adding Fractions

### Tying You Shoes: Square Knot Bow

(Yes, tying your shoes is mathematics too!)

### Tying Your Shoes: Surgeon’s Knot Bow

(Yes, even you can learn something new!)

### Disney’s Donald in Mathmagic Land

A classic of educational video from 1959 that ties mathematics to music, art, nature, and games. IMHO, the best educational feature Disney ever made! (This video has now been removed due to copyright violation…predictable. It was too good to be true. However it is still available very inexpensively on DVD.)

### About The Math Without Borders “Golden Logo”

### The Ultimate Area Formula

Have you ever wondered how surveyors measure the “acreage” of parcels of land? I found a method in a surveyor’s handbook for finding the area of any polygon that I have not seen in math textbooks. It is very simple and it is completely rigorous (i.e. it is not an approximation). I included this method in the supplementary materials for my HSC Geometry program. Check it out here. (I also did a series of videos for the Schoolhouse Teacher site on area, culminating in the Surveyor’s Formula.)