I really like this idea for the younger grades. I am a big fan of students working with others, because I believe that is when you learn best. But there are times when it needs to be independent work and I think this is a great way to monitor the noise level in the classroom.
I love colorful displays, so this crayon classroom door display "Get Ready for a COLORFUL YEAR! OUR NEW PACK" is an idea I'd love to use. This idea would also look great as a Back to School bulletin board display.