@Iluviaporos - That's one reason I would get a very clear description of what they expect you to do before you start as an assistant. Different schools will define them in different ways. You might be working with children who have been identified as needing specific help and expected to develop your own mini-curriculum. Or you might just be chopping up worksheets for a single teacher who needs an extra pair of hands.
If you are just looking for a job, then it doesn't matter so much. But if you really want to help educate kids then you need to make sure that the position is going to be everything you want it to be.