Nowadays most school calendar is planned as one-year activity, in some countries the beginning of the calendar is around September (Europe), in other countries is February or March (Brazil). Because of this when a student moves from one country to another they lose a complete term or year, because is really hard to math this calendar.
Also when a student does not have a productive year they lose a full year, instead school calendar could be six-month period. That way students don’t feel so much pressure by the end of term because of accumulative pressure or content.
