The Module settings card comes with a checkbox for lesson ordering. Selecting this checkbox allows the author to ensure that the lessons inside a module will be completed in the order that they have specified. Each lesson that contains a completion page (report page) will have to be committed before the next one can be started. The padlock icon between each of the lessons shows a completion page that must be committed before the next lesson can be started.
In the example above, the author wants students to commit Part One before starting Part Two, and all three parts must be committed before beginning the quiz.
Once the lesson ordering checkbox is selected, students will see lessons inside that module with lock icons on them. A lock icon on a lesson inside a module is an indication that the prior lesson in the module needs to be completed before the locked lesson will be made available.
If the student attempts to open a locked lesson, they will be advised that they need to complete the previous lesson first.