By registering an account, you will be able to add classes to your personal schedule and thereby use your account as an organizational tool. Furthermore, teachers often send out mass messages to users that have added their class with class updates, new material, and so on, so you'll be automatically kept up to date.
You'll also get an @ureddit.com email address you can check from webmail, your mail client, Gmail account, or smartphone in order to always be up to date!