How can I define lessons that can be outside teaching block(in the afternoon)?

If you have some subjects that can or has to be in the afternoon you can add this cardrelationship:

Now the selected subjects can for example be on 8th period, while normal teaching ends at 5th period. Without this card relationship the software will not create 3 period gap for the students by default.

Notes:
- If you want to limit the maximum gap length the children can have, you will need to add next cardrelationship:
Class can have max 2 gaps per day
- you can also modify the time off for classes and subjects to pack the timetable into less periods, maybe in some cases this is easier than by adding the above relationship