National Library Week Day 4

National Library Week is almost over, but not before we hand out one last puzzle! Today's is a variant of the recently-popular sudoku. But what do the three sudoku grids have in common?

Check out today's puzzle here
http://www.asl.edu/library/nlw.php

Due to the nature of Friday's compressed schedule, we will be having the prize drawings at about 11:15 am. You do NOT need to be present to win!

Good luck!