Effect of Expectations on Achievement
If you let students know that you believe they can achieve a high grade in your class, they already have one person in their corner. Similarly, if you let elementary school students and their parents know that you believe they can meet grade-level expectations in math and reading, you are setting up an expectation of success.
Some students have trouble believing in their own abilities. By constantly reinforcing the idea that they can do it, you are helping them believe in themselves. Eventually, they will internalize the message. Of course, not all students will earn high marks in your classroom, but many of them will make a greater effort to do better than they have in previous classes.
In fact, high expectations for behavior and grades work together to produce a much better learning environment. Students who regulate their own behavior based on your expectations are much more likely to work harder and produce better work.