Your Community Lookup Key, in most cases, can be found on your course syllabus. Otherwise, your professor or TA may have distributed it via email. If you still can't find the lookup key, email us at firstname.lastname@example.org with the name of your professor and your class and we will assist you shortly.
If you were invited to your community by your professor or you were on the initial course roster then you won't actually need the lookup key! Check your email for an email with the subject "Finish registration for Instructor...on Packback Questions". Either login or set a password (if you never registered) and go to the Join a Community page where you'll see the options to either join your community or drop the class.
The community lookup key will have the following format: XXXXXXXX-XXXX-XXXXXXXX-XXXXXXXXXXXX. It can only be used to find your community. The lookup key is not an access code or a coupon so it cannot be applied in the coupon field at checkout.