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.
10 Ways to Sabotage Your Classroom Managment: If you are having classroom management problems, take a look at this article, which explains what NOT to do, and the more effective practices you should try instead.
Disciplinary Chart! Mine would look different but I like this idea! We have a chart right now that I do on poster board and use stickers with happy or sad faces. This would save so much money in the long run and it looks better too!
Put on classroom door? Freebie Classroom Community Building Poster The same theme applies at home to our homework area. Need to make something like this to remind my munchkins (and a reminder to us parents sometimes too).