A module is a container for a group of lessons in a course. Conceptually, they exist as an additional level between courses and lessons in the course hierarchy. A course can contain any number of modules, and every lesson in the course can be assigned to a single module.
To add a module:
You can also add modules when creating or editing a course:
After you have added modules to a course, you can add a module to each of the lessons in that course.
To assign a module to a lesson:
By default, any modules that are added to a course are displayed in alphabetical order. To use a custom order, go to Courses > Order Modules. Select a course, drag and drop the modules into the desired order, and then click the Save module order button.