Expectations matter. When you let your children know that you expect them to give schoolwork their best effort, they are more likely to do well. If you don't expect them to work hard, they probably won't. Or if you make them think they are a poor student, that is what they are likely to be. Expecting your children’s best, however, doesn’t mean expecting perfection. Even the best students make mistakes, and your children need to know that is OK.
Source: The Parent Institute