Preparing teachers is necessary and essential, but it is even more important when they work in a multi-grade classroom, where they must keep in mind how to organize schedules in such a way that they can develop a subject in the same shift for all the grades they teach; study the programmes, methodological guidelines, textbooks and workbooks in order to master the objectives, content and methodological treatment of the subjects to be addressed in each grade; think carefully about the direction of the teaching process and the activities to be carried out in order to determine which ones should be directly directed by the teacher and when the students can work independently.