[@mercime Participant 13 years, 7 months ago]

>>users cannot communicate with, see each other, or even know other users exist). Only the admin will have the privilege of viewing profiles or commenting on users’ blog posts.

@bg01 As I see it, you don’t even need BuddyPress especially with the configuration you posted above.
– Just create a network (go multisite)
– allow students to create own blogs or create the blogs yourself and add student/user per blog
– make all sites private (Super Admin can see anything and everything)
– post comment on each student’s blog post.
If you have any issues with your multisite installation, please post at https://wordpress.org/support/forum/multisite

Alternatively, you can have one single WP site. Make it private, no feeds. Set access of all posts in front end and back end to Site Admin and respective post Author in custom WP theme. Only Site Admin can post comment in all posts.
If you have any issues, please post at https://wordpress.org/support/forum/how-to-and-troubleshooting