# Featured

## Square Pyramids, Difference of Squares, and Amazing Square Patterns

Posted on January 23rd, 2016 by kramer

Pyramids:

## Square Grids Yield Square Number of Rectangles

Posted on January 17th, 2016 by kramer

Last week we explored the amazing pattern of squares withing square grids. The result is always a sum of square numbers such as 1 + 4 + 9 + 16 + 25 ... in a 5x5 grid.

## How Many Squares Are in the Compound Drawing?

Posted on January 7th, 2016 by kramer

We explored the dimensions of our mathematical world. We should not take for granted that children understand the classifications of mathematical dimensions.

## Magic of Adding Numbers with Anti-Nines

Posted on December 19th, 2015 by kramer

**Step 1**: Have someone pick a large number *with any number of digits*.

## Subtraction Magic of Nines — Longevity Calculator

Posted on December 11th, 2015 by kramer

Last week we explored the concept of difference by subtracting birth year from death year to calculate the longevity of scientists and mathematicians. The K-1st graders subtracted using standard algorithm with no borrowing and the older students mastered both borrowing and subtracting with adding.