Locate the module you want to restrict access to. Click the dropdown located at the right-hand side and click 'Edit section'

Click 'Add restriction...' and select options as desired.

It is recommended to use the 'eye', adjacent to any restrictions to choose what happens if a student does not have access to content. 

By default, students will see the name and restriction details but cannot enter the content. It is recommended to cross out the eye to hide content from restricted students entirely if restriction details contain sensitive content (i,e, student details).

Restrict access to a Section