Here's the catch: students are allowed to fail assignments; students are not allowed to fail courses.
When a student fails an assignment, rather than simply marking the student as a failure, the teacher meets with the student and asks some prescient questions: Do you understand the material? (Can we deliver it in a more useful or interesting way?) Are there specific parts you aren't understanding? Там еще много на эту тему.
Это так, разговоры с пространством.