A recent study at the Harvard Family Research Project suggests that high expectations in school lead to high performance.
High expectations move children forward, even if they don't always succeed.
Quotes:
Don't lower your expectations to meet your performance. Raise your level of performance to meet your expectations. Expect the best of yourself, and then do what is necessary to make it a reality.
Our limitations and success will be based, most often, on your own expectations for ourselves. What the mind dwells upon, the body acts upon.