Each course is divided into Topics and their Activities. 

In the example below of the course on Antenatal Care Part 1, the first topic is "Planning Antenatal Care". Activities include Learning Outcomes, What is Antenatal care, maternal and newborn mortality, summary, video quiz, etc.

You've probably already figured out that you can navigate between the activities in a particular section by swiping your phone screen either left->right or right->left.