My mind keeps thinking of all the ways I could use this set up in my classroom - adding (easy numbers at first, sets of 10, then double digits), letters (like boggle), at a station (make spelling words or put some word family endings on there instead of just letters). I keep thinking about how much fun Scramble with Friends has been this summer on my iPhone!
Math Boggle ... Kids choose two numbers that are next to each other, and perform the circled operation. Clever!