User groups

Hello,

I need to create a website for a school.
It's something just intended to act as a bridge between the teacher ans the students, that they can share with their parents.

There will be profiles of teachers, students.

The teachers will manage only the profiles created by the students in their group. They should be able to modify their own profile and their student's.

But not the profiles of other teachers or other teacher's students.

The teachers must be able to approve and modify their student's profile in the frontend.

Can this be achieved with Community Builder and Joomla ACL?
Do I need other extensions than basic CBuilder?
If so, which ones?

There's no way to do that easily as there is no user by user moderation. Someone is either a moderator or they aren't. Moderators can't edit other moderators so a teacher editing another teacher couldn't happen, but anyone that's a teacher would be able to edit any student. If that's acceptable then CB would work for you. You may want to look into using something like Moodle which is designed for what you're wanting.