Students do not stop living the timetable at the last bell. They carry it home. A Tuesday with Mathematics, English, German, French and Chemistry is five sets of exercises due on Wednesday. A Thursday with Sport, Art and Music is an evening off.
No teacher set out to overload Tuesdays. The timetable put those five subjects on the same day, and homework follows lessons. This article is about treating that as a scheduling rule rather than an accident.
The homework calendar nobody sets
Most schools have a view on how much homework is reasonable. Very few have one on when it arrives, because that is not a teacher's decision. A teacher sets homework for the next lesson, and the next lesson is wherever the timetable put it.
An illustrative week for one class, counting only subjects that routinely set homework:
| Day | Homework subjects that meet | Count |
|---|---|---|
| Monday | Mathematics, English | 2 |
| Tuesday | Mathematics, German, English, French, Chemistry | 5 |
| Wednesday | Mathematics, German | 2 |
| Thursday | French | 1 |
| Friday | Mathematics, German | 2 |
Twelve in total, a perfectly normal load. The problem is not the amount but the shape: the same twelve could sit as 3, 2, 3, 2, 2. A generator will not care unless you tell it to. To the solver, Tuesday is simply a day where those lessons fitted.
The rule: distinct homework subjects per class, per day
In Bildena the rule is two settings that work together:
- On the subject: a checkbox, Requires homework preparation, in the subject's constraints. It marks the subject as one that counts.
- On the class: Max homework subjects per day, in the class's constraints, a number from 1 to 8. Left empty, there is no limit.
The solver then guarantees that for every class with a limit, on every day, the number of different marked subjects that meet is at most that number. Three details of the counting matter:
- A subject counts once per day, however many hours it has. A double of Mathematics, or Mathematics in period 2 and again in period 6, is one homework subject for that day.
- Shared lessons count for every class in them. Chemistry taught to two classes together uses a place in both classes' limits.
- It counts at the level of the class, not the group. If a class splits into French and Latin groups and both are marked, both count toward the class's limit that day, even though no student takes both.
Which subjects should count
The instinct is to mark everything that ever sets homework. Resist it. Every marked subject is one the solver has to keep apart from the others, and the more you mark, the less room is left for everything else you care about.
A workable start is the subjects where homework is regular and substantial. In most secondary schools that means the main subjects: Mathematics, the language of instruction, the first foreign language, perhaps a second language or a science in older years. Sport, Music, Art or a weekly project lesson usually should not count.
The mark is per subject and applies in every class that has that subject. The limit is per class, so a younger year group can have a tighter cap than an exam year.
A hard rule, not a preference
Bildena enforces the daily homework limit strictly. It is not a weighted wish the solver trades against teacher gaps; a plan that breaks it for any class on any day is not a valid plan. Our article on teacher gaps and student gaps explains the difference between hard rules and weighted preferences.
Strict is the right default here, because "at most three, usually" is not something a class teacher or a family can rely on. But it means the number has consequences. If the rest of your data leaves no arrangement where every class stays under its limit every day, the run will not produce a timetable.
So you soften the rule through the number and the marked subjects, not through a weight. A limit of three with four marked subjects is a gentle nudge. A limit of two with six is a strong shaping rule. For orientation: most of the sample school templates that ship with Bildena use two, a good number use three, and a handful use one.
Do the arithmetic before you run
The first check Bildena does for you. Before a run, the Advisor counts each class's distinct marked subjects against its limit and the length of the week. Eleven marked subjects with a limit of two need at least six days; a five-day week cannot do it, and the Advisor reports a critical issue with the ways out: raise the limit, unmark a subject, reduce hours or add days. It also lists classes that have marked subjects but no limit, so you know the rule is not applied to them.
The second check no simple count will catch, so do it by hand for your tightest class. Think in subject-days, not subjects. A limit of two on a five-day week gives ten subject-days. Now look at what your other rules consume:
- Mathematics, five hours, at most one lesson per day: five subject-days.
- German, four hours, at most one per day: four.
- English, three hours, at most one per day: three.
Three subjects and a limit of two looks comfortable. In subject-days it is twelve into ten, and no timetable exists. No single setting is wrong; the combination is impossible.
How it pulls against other rules
The homework limit rarely causes trouble alone. It causes trouble by narrowing the choices every other rule relies on.
Doubles help it. Because a subject counts once per day, bundling hours reduces subject-days. Five hours of Mathematics as two doubles and a single meet on three days, not five. In the example above, allowing one double each in Mathematics and German brings the total to ten, and the week is at least arithmetically possible again. The limits of that approach are in our article on doubles and distribution.
Spreading rules pull the other way. "At most one lesson per day" is often the right rule for a main subject, and it is exactly the rule that makes that subject occupy the most days. Main subjects are also the ones most likely to be marked, so the two rules compete for the same capacity.
Teacher availability fixes days. A part-time teacher who is in on Tuesday and Thursday takes the choice of days away for that subject. For one subject, fine. When two or three marked subjects share teachers with the same two days, those days fill quickly and the limit pushes everything else onto the other three.
A way to set it up that works
- Run without the rule first. Leave the limits empty and generate. Count marked subjects per day for two or three representative classes. If no day goes above three, you may not need the rule.
- Mark only the subjects that matter, and think twice about split language groups.
- Start loose. Set a limit one above what you would ideally want, check the Advisor, run. Then tighten by one and run again. Compare the two plans on what else you care about: teacher gaps, doubles, late lessons.
- Tighten per year group. Younger classes with fewer marked subjects can usually take a lower limit than exam years.
Both settings belong to the school year and are carried over when you set up the next year from the current one, so this is work you do once rather than every summer.
Most of what a timetable decides is visible in school. The evening load is not, which is why it is so rarely designed. A daily cap on homework subjects does not make homework lighter. It makes it even, and for many classes that is the more useful of the two.
Both settings sit in the constraints of subjects and classes, and the Advisor checks the arithmetic before every run.