Teachers play a huge role in children's lives. The main purpose for having a teacher is to guide you to the correct path and to teach you things that you might have not known before.
A person can think, "We can learn at home from our parents and our parents are also there to guide us. So why do we need to have teachers?" To express my thought, I want to give you a brief description. For example, in New York, kids have to take a State Test that measures how much the student has learned. To make students pass, before the test date, teachers prepare students to do their best. However, if you ask your parents, they wouldn't know much information about it, since teachers could've taken a specific training to help students. The same curriculum applies to many other places.
In other words, teachers are here to help students know varieties of things that students didn't know before. Teachers are also here to help us go to the correct path. Furthermore, teachers are like our parents when we don't have our parents during school time. You can position teachers right after your parents.