We need that class after lunch would have the same lesson as before lunch (for lessons which count is 2 per week)

COVID-19 case

So pupil can have lunch in the classroom, and then continue lesson in the same classroom.

For example:

Class 10A: English lesson – Lunch – English lesson; other day: Biology – Lunch – Biology
Class 10B: Math – Lunch – Math; other day: Chemistry – Lunch – Chemistry

First set one period for these classes for lunch, e.g. period 4:

Set distribution of lessons over the week: lessons that are 2 per week must be placed in 1 day per week:

And this additional condition:

Result:

Set similar relations for classes that have lunch break on other periods, e.g. on 5-th or 6-th lessons.