Algodoo

Two rectangles (one blue and one red) are made up of exactly the same number and sizes of smaller shapes. But when the shapes are arranged differently, the total surface area is different! How could this be?

No need to start Algodoo. Simply grab and move the red shapes over to and on top of the blue shapes. You will need to rotate two of the shapes by 90 degrees. When all red shapes are on top of the blue shapes, you will be convinced that they are exactly the same size and shape! But when rearranged, the resulting rectangles have different surface areas! How is this possible?


Here is the explanation.