Challenge!
How many squares?
Hint:
Guess and check or trial and error.
There are four different sizes.
Discussion:
Mind boggler!
How many rectangles?
A rectangle has to have a white edge all the way around. It can have another white line bisecting it, but can't draw through another figure.
Yes, A square is a rectangle, but we know how many of those there are since that was the first challenge!