From a 2nd grade teacher friend:
We are studying statements, commands, exclamations, and questions. I say a sentence. If it is a question they stand up and curve their arm over their head like a question mark. If it is a statement, they put their head on their desk like a period. If it is an exclamation they stand up straight with both hands over their head like an exclamation mark. My kids loved it!
Squarehead Teachers 
Another great idea. I want to try this with my class. 🙂
Thanks!