Subtraction of Notable Products

The idea is for children to understand why the square of a subtraction is NOT the square of “a” minus the square of “b”.

We start with the frame and place the square of “a” in it. If we now place: first the vertical rectangle “ab” and then the horizontal rectangle “ab”, it can be understood that we have removed the square of “b” twice from the square of “a”. For this reason, we now include the green square of “b”, that is, we add it, and what remains: the result is the square of the difference.

a2-2ab+b2=(a-b)2

In my opinion, for good understanding, it is important to print the file with different colors.