groups VS rooms

[yahi]

from   colleague "AISSE" One of the  problems we meet  in PREPARING  TIMETABLEs is the case  when  the number  of  groups " classes " exceeds  the  number of  class-rooms i mean here  you have  20 groups   and 15 rooms  only .how  to manage in such a  case .personnally as  a  user  of  fet i did  not met such a  trick as my school has extra  rooms .thanks in advance 

[Volker Dirr]

I am not sure if i understood correct.
I guess you need 2 things:

1. you must be able to detect those problems as early as possible.
so the first trick is that all activities must have a space constraints.
Check FET -> Statistics -> Activities rooms statistics.
Now you will notice hopefully early enough that the timetables is not solve able because of missing rooms.

2. The seconds things is you need to fix that problem. Sadly very difficult to answer how to do that without seeing the dataset. In "normal" case you need to allow more timeslots and are prefer special slots for those activities. So maybe those activities will be taught normally at the end of the day (of course at least 2 different days). So other students can go home and don't get gaps.