'Teachers have a lot to do with their students' motivational level. A student may arrive in class with a certain degree of motivation. But the teacher's behavior and teaching style, the structure of the course, the nature of the assignments and informal interactions with students all have a large effect on student motivation. We may have heard the utterance, "my students are so unmotivated!" and the good news is that there's a lot that we can do to change that.'
This site from SERC provides some advice for motivating students and includes references.