Our school (culinary) has adopted a four catagory system that weights each catagory by a percent value. Sounds confusing, but actually it's fairly simple and our students really like it. We base it on competencies, professionalism, quizes and attendance each is weighted by a percentage. We also have cut and dry policies on make-ups, late project work, attendance and tardiness. We do have the option to offer "extra credit" on quizes or "open note books", but it must be available for all students. For me and the way our program is structured...allowing individual instructors to use their own grading system is frankly quite scary.