If the course coordinator has a firm policy on submission dates and reasons that are valid passports for extensions and this is clearly communicated to students, you should support the coordinator.  It certainly makes things easier for you.  

If you are left to decide on the submission dates it is a good idea to talk this over with your class.  This allows you to come to an agreement with your students and if any students try and go outside this contract you can refer to the earlier 'treaty'.  

It is useful to remember that in the normal course of events, students can be encouraged to submit work on time if:  

·        You collect their work when it is due.  Students are peeved if they walk past your box and see their assignment uncollected for days.  

·        Endeavour to return marked work at the agreed time.  A one to two week turn around is usual.  

·        Where possible help students to complete work.  That is, make clear what is expected and be willing to help students in difficulties or suggest where they can find assistance.  

·        Make course coordinators aware of unreasonable time frames for the submission of work.