You'll need a Join Code if you're a student who is eager to participate in a Pear Deck class. You'll usually get this code from your teacher.
JoinPD.com

It's likely that many of you recall JoinPD.com as the preferred domain in the past to access Pear Deck classes. However, in order to improve user experience and guarantee security, Pear Deck has recently moved its attention to PearDeck.com, its main domain.
JoinPD.com