Gateway Exams provide a simple and effective way of encouraging students to take responsibility for learning essential skills such as algebraic manipulations, differentiation, and integration. The goal is to insure that each student possesses, by certain predetermined dates, the skills necessary for success in the next segment of the course. Gateway Exams can also be used at the beginning of a course to make sure students have mastered prerequisite skills.
Gateway Exams are individualized, computer generated, no partial credit tests, with a near perfect score required for passing. Each student gets multiple opportunities to pass each exam, instant feedback upon completing an exam, and instant advice about how to fix what went wrong. Failure to pass a given exam within the designated time period results in some kind of grade penalty.
You can find further details about the Gateway philosophy, at Robert E. Megginson's Gateway Web Page at The University of Michigan.