New Geometry product on horizon from Singing Turtle Press. Math author Josh Rappaport is coming out with an eBook on geometry. Read this post to find out more!

# Archive | Logic of Geometry

# Rubik’s Slide: play your way to geometric knowledge

The people who gave us the Rubik’s Cube recently came out with another fun puzzle, the Rubik’s Slide. This post tells all about this fun puzzle, which actually helps students learn some geometric concepts.

# Invisible Misunderstandings: Square roots of 2 and 3

There are large chunks of mathematical knowledge that we often assume students have down. In fact, they often lack that knowledge. A good example is this: most students I work with have virtually no sense as to the value of the square root of 2 or the square root of 3. This post offers a […]

# Origins of the Coordinate Plane

One of the legends of math relates to the invention of the coordinate plane system. The legend states that Descartes was inspired to invent this system after watching a fly move around on the ceiling over his bed. This post tells the story and points out its relevance for modern math teachers.

# How to Use Definitions in Geometry

Definitions are TWICE as useful as standard theorems in geometric proofs. This post explains why, showing that definitions are, in a certain sense, very much like “reversible coats.”

# ANSWER TO FRIDAY’S PROBLEM:

Answer to Friday’s problem, regarding the number of diagonals that can be drawn in any convex polygon.

# Challenge Problem – Polygon Diagonal Formula

Polygons have diagonals. There is a formula for the number of diagonals that a polygon has. For a challenge, find the algebraic formula that governs how many diagonals there are in any convex polygon with n sides. Good luck!