Question

After families, schools are perhaps the most important and obvious means through which children learn social norms, values, and beliefs.

Answer 1

Yes, I think that this is true.

One reason for this is simply that children spend a significant amount of time at school: so it's very likely to influence them.

Another reason is that the school is the context in which the children are introduced to many ideas; and often the first introduction to an idea is the most formative.