How to Avoid Room and Teacher Clashes in Your Timetable

A teacher booked for two groups at the same time, two groups turning up at the same room, a group of 12 squeezed into a room with 6 seats. Almost every course center has been there. When the timetable is small, you can keep it all in your head. But as the number of groups, teachers and branches grows, clashes become routine.

Why clashes happen

Most clashes have the same causes:

• several people edit the timetable in separate files;
• a change is made in one place but not updated in another;
• a teacher works at several branches, and their overall schedule isn't visible anywhere;
• a one-off change (an extra lesson, for example) never makes it into the main timetable.

Worst of all, a clash is usually discovered not when the timetable is drawn up but on the day of the lesson, when students are already at the door.

Build the weekly timetable step by step

1. Gather your constraints

Before you start on the timetable, prepare three lists:

• Rooms: the capacity and equipment of each (a TV, computers, a whiteboard).
• Teachers: which days and hours they can work, and which branches they teach at.
• Groups: the number of students, lessons per week, lesson length and suitable times.

2. Start with the hardest groups

Place the groups with the most constraints first: students who can only come in the evening after school, a teacher who works only on certain days, lessons that need special equipment. Fitting in the more flexible groups afterwards is much easier.

3. Three checks for every lesson

Each time you add a lesson to the timetable, answer three questions:

1. Is the room free at this time?
2. Is the teacher free at this time, including at other branches?
3. Is the group free at this time?

If you have to check these by hand every time, sooner or later one of them will be missed. That's why having the check done automatically is the most reliable approach.

4. Leave gaps

If a teacher moves between branches, allow for travel time. A short break between back-to-back lessons in the same room lets you air the room and gives the next group time to settle in.

Don't forget room capacity

A free room isn't necessarily a suitable one. Putting a group of 10 into a room with 6 seats isn't technically a clash, but the lesson won't go well. Record the capacity of each room, and whenever a new student joins a group, check that the room still fits. When a group grows gradually, this check is very easy to forget.

Substitutions

When a teacher is ill or on leave, someone else takes the lesson. A few rules for substitutions:

• Check that the substitute is free at that time: they may be teaching another group.
• Record the substitution as a one-off change and leave the main timetable untouched.
• Note who actually taught the lesson. You'll need this later when counting teachers' hours and tracking which topics were covered.
• Tell the substitute in advance where the group is up to and which topic was covered last.

Communicate changes

Even the best timetable changes: public holidays, exam periods, a room under repair. Once a change is made, the key question is who needs to know about it:

• the students in the group and their parents;
• the teacher of that lesson, and the substitute if there is one;
• other groups whose times shift, if the change affects them too.

The message should be specific, for example: "On Wednesday at 18:00, the maths lesson will be held in room 5 instead of room 3." A vague "There's been a change to the timetable" only leads to more questions.

Announce changes as early as possible, not at the last minute. If a parent drives their child to the lesson, a message sent an hour before may already be too late.

A weekly check

At the end of each week, spend 10–15 minutes on the next week's timetable. Are one-off changes, substitutions and holidays recorded correctly? Has everyone affected by a change been told? This short check saves you from confusion on Monday morning.

How a system like Zehinly helps

In Zehinly, room, teacher and group clashes are blocked while you build the weekly timetable, before a lesson is saved. When the timetable changes, students and teachers are notified. Each branch has its own manager, and the owner sees all branches. You can try it for yourself in the free online demo.