Course Structure is fixed (and by course structure, it is meant as the technical structure, not the contents of the course) The hierarchy is organised into parents and children where one type of object is a parent or a child to another type of object. It’s easier to see it visualised:

From Parents to Children:

Units→Skills→Lessons→Questions #

Units contain skills, skills contain lessons, lessons contain questions.

It’s easy to navigate between each layer, every time you double click a parent, the sidebar goes down one layer

→ #

Clicking the Menu button

will take you back to the top. (Units)