заучи is an interesting word. Neither wiktionary.org or Google Translate knows that one! However, Google Translate does recognize завучи as "head teachers" along with "Главные учителя." Are заучи and завучи interchangeable or was заучи just an inadvertent typographical error?

So the hierarchical structure at and elementary school for the teaching staff is teacher (учитель), head teacher (заучи/завучи), and principal (директор), right? Here in the USA very few schools have recognized "head teachers." However, senior teachers (those who have been around for awhile) are generally recognized, implicitly, as having a bit more authority. What about instructional aids? Many schools have instructional aids working in the classroom. Usually these are people with very little formal training and with no teaching credential. First of all, are there paid instructional aids in Russian classrooms? Secondly, if so, what are they called?