Prospective students can signup for a waitlist when the class is full.
If the student is logged in, they'll be automatically added to the waitlist when clicking the sign up button. Otherwise, the prospective student is prompted for their first name and email address.
All students on the waitlist can viewed in the Waitlists tab in the Classes admin page. You can remove students from the waitlist using the bulk actions dropdown or clicking the Remove link underneath each record.
Waitlisted students can be manually notified by selecting a class from the dropdown and pressing the send button. Only classes that have seats available will appear in the classes dropdown.