Sometimes when children are finished I give them a challenge called the squiggle. Basically I draw some kind of line or lines on a paper with a black marker. The challenge for the student is to take that line and turn it into something. I decided to give these two students the exact same squiggle and told them not to let the other see what they were turning it into. You can see my darker lines in both and you can also see the two different solutions to the same problem.