** How to make that one class does not outrun other class by some subject lessons**

For example:

The teacher teaches mathematics in three classes – 7A, 7B and 7C, and each class has three lessons per week. This relationship allows lessons to be arranged in a week this way, that any of these classes bypass others in the curriculum.

E.g. the first lesson (out of three per week) would be for 7A, for example, on Monday, and the first for 7B and 7C, for example, on Tuesday. The second math lesson for all classes on Wednesday, and the third – on Thursday and Friday.

Thus, this condition determines: The first lesson of the subject must occur for all classes, and only then the second lesson can take place.