Simply be certain to include any and all you are requiring or permitting specifying whether they are in fact required or optional, along with any due dates and other relevant information. Grading Scheme Decide in advance of the class how you will determine grades. Specify in the syllabus the grading scheme you are using and make it sufficiently clear in order that students may track their grade throughout the class. This is the time to specify whether any scores may be dropped, how scores will be cumulated into some sort of overall grade, including the weight accorded to each piece of graded work. While there may be some need to remain flexible in the grading scheme to accommodate unanticipated glitches, it is best if you adopt a scheme and stick with it.
Ambiguity only leads to misunderstanding and trouble.
It is usually your decision whether to let students make-up missed exams or whether you will accept late work. Simply decide in advance what your policy is going to be, put it in writing in the syllabus, and stick with it. In the rebate, students redo work in an effort to gain back a certain portion of that which was discredited.