PADI's eLearning option that lets you study independently at your own pace before class. There are nine interactive knowledge development sections. Prestudy online saves classroom time, which allows more time for practicing the skills that distinguish you as a PADI Instructor.
Also, sign up for Dive Theory Online, if you haven't already completed it or it's been more than a year since you went through it. The program is a straightforward review of dive physics, physiology, skills, equipment and environment, plus using the Recreational Dive Planner (RDP). By successfully completing Dive Theory Online, you can get credit for the dive theory exam requirement during your IDC.