Modules are used to organize course content by weeks, units, or whatever organizational structure works for your course. With modules, you are essentially creating a one-directional linear flow of what you would like your students to do. Once you create modules, you can add content items, set prerequisites, and add requirements.
Lock Module Date
If you want to restrict the module until a specific date, you can lock the module.
Add Module Prerequisites
If you have added at least one module to your course, you can require a prerequisite module. A prerequisite module means students must complete the added modules before they can view the new module.