You can set Modules to be locked until a given date.

You can add requirements for a Module that students must meet before they can move to a following Module.

You can set up your Modules so that students must complete one module before moving to the next module.

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.