Look at the following figure. Copy the cross onto another piece of paper. Then, cut apart the four pieces labeled A, B, C, and D. You now have a jigsaw puzzle with four pieces. Can you figure out how to put the pieces back together to form a square?

Answer:
C should slot on top of A.
Then D should slot in next to C of the left.
Lastly B should be beneath D and on the left of A.
Hope that makes sense.