Tracking Student activity

Hello,

I would like my students to spend 15-20 minutes each day on MAP Accelerator and I would like to keep them accountable by giving them a grade for their efforts.  How have others done this?  What MAP shows as "learning time" seems much less than actual time spent on the program.  For instance, it might show that a student's learning time was 5 minutes but that they completed 20 questions.  This does not show ACTUAL time spent on the program it would seem.  Thoughts?