# Tag Archives: geometry

## Quadrilateral Puzzle

I’ve been immersed in puzzle and lesson creation lately, and I thought I should take advantage and throw some of them out here on the blog. Please take, solve, use in your classrooms or at home, and let me know … Continue reading

## Pythagorean Theorem Part 1 (Video)

I finally tried my hand at a video explanation of a mathematical idea I like. This is part 1 in a short series on the Pythagorean Theorem. It starts where I’ve always felt the story should start: with the question … Continue reading

## Midpoints of a quadrilateral form a parallelogram

Take any quadrilateral, like this one then mark the midpoints, and connect them up. It sure looks like a parallelogram, doesn’t it? The amazing fact here is that no matter what quadrilateral you start with, you always get a parallelogram … Continue reading

## Billiard Balls and Laser Beams: Talk, Slides, and Videos

I had the opportunity to speak at the University of Washington Monthly Math Hour on April 17. Following my talk a six and a half year old named Rebekah gave me this drawing she drew during the talk. The talk, … Continue reading

## Student Proof: connect a point on a circle to the two endpoints of a diameter, and you to get a right triangle

A few weeks ago a student and I noticed that if connect a point on a circle to the two endpoints of a diameter, you seem to get a right triangle. After working for a bit, we came up with … Continue reading