# Featured

## Square Grids Yield Square Number of Rectangles

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?

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

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

## Subtraction Magic of Nines — Longevity Calculator

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.

## Longevity — Life Expectancy — Scientists and Mathematicians — Subtraction Standard Algorithm and Addition Method

After reading 15 math challenge poems from the world’s greatest poets, the children were interested in their biographies.