Here's a little something that I do with my kids at the beginning of the year to help cultivate classroom culture. I believe I found it in the Mailbox Magazine years ago.
It all starts with 25 puzzle pieces like these.
I trace the puzzle pieces on two poster boards. One poster board gets cut apart and numbered on the back of each piece. The other poster board is left intact. Each piece is numbered on the front.
After each child draws themselves on a piece (on the side that isn't numbered), they bring it to the intact poster board, find the matching piece using the shape or number as help, and then glue it on.
When complete, we fit together pretty well.