Some of you know that I am a mathematical philosopher, so you may be surprised at the title. After all, all squares are rectangles.
But some rectangles are not squares, ... but they can be made thus, and here's how.
Let's take a rectangle that's 8½" x 11".
If you fold it in half one way, you have a rectangle that's 8½" x 5½".
Turn the rectangle so it's "standing tall." Fold the top right corner down to the center left side. You now have a quadrilateral. Fold the top left side down to the left center, joining where the top right corner was folded, you now, again have a rectangle, but now it's 5½" x 2¼".
This fold, by the way, is called the "I love you" fold, and many letters of love are sent folded this way.
Now, seal that love closed for your beloved by folding the bottom half up into the triangular lip. You now have a 2¼"x2¼" square from an 8½"x11" rectangle.
How do you make a rectangle into a square? It's neither instant nor easy, but, the recipe is simple: just add love to a piece of letter writing paper, and then seal that love in.