Constraint recipe
A double-period lesson uses two adjacent teaching periods as one session, common for labs, workshops, and practical work. Both periods must be free together for the teacher, the class, and the room, so a double has far fewer valid placements than two singles. Check availability across the full block, and place the tightest blocks first.
Key takeaways
- A block needs two adjacent periods with the same teacher, class, and room.
- Separate curriculum-required blocks from merely preferred ones.
- Check availability across both periods, not just the first.
- Place the most constrained blocks before flexible single lessons.
Why blocks are harder than single lessons
A single lesson can use any free period. A double period needs two neighboring periods where the teacher, class, and room are all free at once. That smaller set of options is why experienced planners place the most constrained items first: lab and workshop blocks early, flexible singles last.
Mark a block as hard when splitting it would make the session unusable, for example a practical that needs setup and cleanup inside the session. Keep it soft when adjacent placement is desirable but the lesson still works as two singles.
A worked example: where can the science double go?
Class 8A needs one science double per week with Ms. Petrov in the lab. The obvious slot fails: Thursday P5 and P6 looked free for the class, but Ms. Petrov is unavailable in P6. A double is only valid where two adjacent periods pass every check.
Ms. Petrov's week: the double fits Tuesday P3+P4
| Mon | Tue | Wed | Thu | Fri | |
|---|---|---|---|---|---|
| P1 | 9B | 7C | |||
| P2 | 9B | 7C | 7C | ||
| P3 | Sci 1/2 | 9B | |||
| P4 | Sci 2/2 | ||||
| P5 | 8A? | ||||
| P6 | Unavail |
- Other lesson
- Valid double placement
- Failed attempt
- Teacher unavailable
Decide before generation which subjects truly need blocks. A whole course rarely needs every session doubled; often only the practical weeks do. Every unnecessary block removes flexible slots from the rest of the week. The curriculum rules guide explains how block needs and spread preferences fit together.
Plan the blocks before the singles
- List the subjects or activities that need adjacent periods, and mark which blocks are curriculum requirements and which are preferences.
- For each block, check the teacher, class, room, and equipment across both periods, as in the example above.
- Place the most constrained blocks first: scarce rooms and specialist teachers before anything else.
- Review whether the blocks crowd one day or overload one teacher's consecutive run.
- If placement fails, relax preferred blocks first and leave curriculum blocks alone.
Block-planning mistakes
- Doubling every lesson in a subject when only some sessions need it
- Checking room availability for the first period but not the second
- Adding new blocks after generation and forcing a full rebuild
In Smootables
Smootables does not pair two separate lessons into a block; instead, a double session is one lesson with a longer duration. Set the lesson length in minutes on the placement, and the generator places it as one continuous session, so the two halves can never be separated.
The reverse operation exists after generation: Split lesson in half turns one long placed lesson into two, when a term's plan changes and the double is no longer wanted.
- Enter the full session length as the lesson duration instead of creating two linked lessons.
- Use Split lesson in half on a generated timetable when a double should become two singles.
Quick answers
Should double periods be scheduled first?
Usually yes, especially when they need scarce rooms or specialist teachers. The most constrained items get placed while options still exist.
Can a double period be soft?
Yes. If adjacent placement is desirable but not required, treat it as a preference rather than a must-have rule.