Using Dollar Store puzzles and a permanent marker, I was inspired to write the numbers on the back of her puzzles. She may have been only 4 at the time but she wanted to do them all by herself. So, I obliged. I did offer a little helping hand by sorting out the pieces 1-10, 11-20, 21-30 and so on into little bowls.
This is still a loved activity at 5. It helps greatly with number recognition and number sequencing.