School timetable guides
What to do when the timetable generator leaves lessons unplaced
Generation can finish with some lessons still without a place. This is a reason to review inputs and restrictions, rather than delete required sessions. Start with the unplaced-lesson list: it identifies the class, subject and teacher that need attention.
Open automatic modeRead the reasons for a specific lesson
- After generation, open the timetable and Unplaced lessons. Check the subject, teacher and class in the relevant view. Read every listed reason rather than relying only on the remaining count.
- Several causes may appear: teacher unavailability, a busy class, a subject restriction or insufficient consecutive periods. The list describes the candidates considered; it does not mean every reason blocks every cell.
Compare the plan with the grid’s capacity
- Count teaching periods across the active days; breaks are not places for lessons. Check the weekly session count and duration separately. A duration-2 session uses two periods even when it has one card.
- For a fractional requirement, inspect both weeks of the cycle. Compare cycle totals with the periods available over the cycle. Check the grid of the class and its requirements, especially across different shifts.
- A long session needs a suitable run of periods within one day. The total number of empty cells alone is insufficient. Compare the available run with any duration or consecutive-lesson message.
Find a restriction that can be corrected
- For a teacher-related reason, open availability and the view of all that teacher’s lessons. Check real clock times across grids: an empty class cell does not necessarily make the teacher free.
- For a subject-related reason, check blocked periods, the daily maximum, spacing and sequence rules. Correct inaccurate values. An acceptable preference can become soft; retain genuine unavailability as essential.
- Do not delete required lessons merely to obtain a fully placed result. When the plan exceeds the school’s capacity, agree on the workload, teaching hours or availability instead of hiding the mismatch.
Save changes and review the entire timetable again
- In automatic mode, save the modified step and generate again. Compare the remaining count and the class and teacher views. Resolving one cause does not rule out another.
- In manual mode, the queue also contains lessons you have not placed yet. Their presence alone does not establish an impossible plan. Place a card in a suitable slot or use automatic completion, then inspect warnings and workload totals. Export after review.
Common questions
Do unplaced lessons prove that a complete timetable is impossible?
Not always. Incorrect inputs, unnecessary restrictions or the generator’s chosen placements can leave lessons unplaced. A remaining lesson is not proof that no complete arrangement exists. Review the reasons and essential requirements.
Why are cells empty when a lesson is still unplaced?
A cell may be unsuitable for the teacher, subject, grid or session duration. Check the class, teacher and rules together; a long session needs several suitable consecutive periods.