I really like the idea and my kids will
LOVE it. But do you put restrictions on the assignment that it can be used for? I'm afaid that they may use it on an assignment that would be particularly helpful or that it would keep them from being prepared for the next day. Especially since We're prepping for the BIG test.
I will frequently give a blanket "no homework" for the whole class, and you would think they won the lottery! In that case I can make sure that the work is made up in some other manner.
Happy Valentine's Day