Students can always view the School Feed. They can see school-wide posts, posts intended for their grade level, and posts for groups, classrooms, and clubs that they belong to.
Students can like posts they are permitted to view, even when they are not allowed to comment.
Whether students can comment on or create School Feed posts depends on the chosen rights for the School Feed.
To change these rights, go to:
School Feed > Feed Mgmt > Posting Rights > Student Settings