I like this saying because it encourages that mistakes are ok to make. I expect my students to show effort in the work that they do, and mistakes are fixable and acceptable as long as they keep trying. I would put this saying on a poster (on vinyl sticker like the one here) and keep in my classroom to remind students that it is ok to make mistakes.
Interactive Bulletin Boards--Great site for finding ideas for interactive math bulletin boards (mostly middle school and high school). Their 5 basic requirements: 1) It has to be EDUCATIONAL. 2) It has to be FUN. 3) It has to be INTERACTIVE. 4) It has to have an accompanying WORKSHEET. 5) It has to count for CREDIT, either normal or extra. LOVE THIS!