How to Prepare a School Timetable? A Step-by-Step Guide

At the start of every academic year, one of the biggest tasks awaiting assistant principals is the timetable. Even a medium-sized school has 30-40 teachers, 20-30 classes and hundreds of lesson hours per week. Trying to solve a puzzle of this size by hand can take days, sometimes weeks.

The difficulty comes from the sheer number of constraints: a teacher cannot be in two classes at the same time, a class cannot have two lessons at once, some lessons require block hours, and some teachers are not at school on certain days. As the constraints multiply, a manual solution quickly becomes impossible.

Before you start, the following information must be clear: the class list (by section), the lesson list with weekly hours for each, the teacher list with their subjects, special rooms such as labs, and the daily period layout (when each period starts).

• Classes and sections (e.g. 9-A, 9-B, 10-A)
• Lessons and weekly hours (e.g. Mathematics 6 hours)
• Teachers, their subjects and weekly teaching loads
• Classrooms and special spaces (lab, gym)
• Daily period layout and break durations

Decide which teacher will teach which lesson in which class. This matching is the skeleton of the timetable. At this stage, check whether each teacher’s total weekly load complies with regulations and their contract — an overload noticed later can force you to rebuild the entire timetable.

There are two kinds of constraints. Hard constraints can never be violated: no conflicts, a room assigned to a single class at a time. Preference constraints should be met where possible: placing physical education in the last periods, mathematics in the morning, honoring a teacher’s free-day request. A good timetable satisfies all hard constraints and as many preferences as possible.

In a small school (5-6 classes) an experienced assistant principal can build the timetable by hand or in Excel. But as the number of classes grows, the number of possible combinations grows exponentially, and missing conflicts by hand becomes almost inevitable.

This is where timetable software comes in: it evaluates all constraints at once and produces a conflict-free schedule in minutes. In a web-based system like DEPRO you enter your data once, generate the timetable with a single click, and update it in seconds when a change is needed.

The work does not end once the timetable is ready: teacher leaves, new assignments and lesson changes continue all year. Using a system that announces your timetable through a single channel and sends automatic notifications on changes makes year-round management far easier.