Drupal Schools Network

I'd use Prosepoint (or your own version of it) if you'll allow students to write blog posts. Example: http://prosepoint.empowered-teacher.com - it uses Panels and "channels" so there can be posts around various topics.

But if that's too complex, still I would use blogs (so students can post their own, and comments can be added - you can make your own teacher blog post available to anonymous users, and only logged in students can see their posts if you like).

Simplenews is more of a publication than a Web 2.0 learning tool - and why limit yourself to that? Particularly when you have Drupal.