Constraint recipe
Room restrictions decide which spaces may host a lesson. A must-have restriction means the lesson cannot run elsewhere, for example a science practical in a lab. A preference means you would rather use room 12 but could use room 14. Mixing the two produces timetables that look complete but cannot be taught.
Key takeaways
- Must-have room types block wrong placements; preferences guide choice.
- Capacity and equipment belong in the same check as room type.
- Too many preferred rooms marked as mandatory creates false clashes.
- Set room rules before generation, not after.
Requirements versus preferences
A chemistry practical in a standard classroom is not the same lesson. A must-have room rule protects that difference. A preference for a familiar room near the staff base is a quality choice.
When every preferred room becomes mandatory, the timetable may fail even though a valid room exists.
What to record for each room rule
Capture room type, capacity, equipment, and availability together. A lab that is the right type but too small for the group is still the wrong room.
See room and equipment constraints for the full checklist.
What to do next
- List subjects or activities that require a specialist room type.
- Separate must-have room types from preferred rooms.
- Record capacity, equipment, and availability for each eligible room.
- Count whether each lesson has enough eligible periods in the week.
- Relax preferred room rules before weakening specialist requirements.
- After moving a lesson, recheck teacher and class clashes as well.
Common mistakes
- Making every teacher's favorite room mandatory
- Ignoring capacity on an otherwise correct room type
- Adding room restrictions after generation instead of in the master data
Quick answers
When is a room restriction mandatory?
When the lesson cannot run in the wrong room type or without required equipment.
What should stay a preference?
Familiar rooms, proximity, and comfort choices usually belong in the preference set.