In order for student to view the Module folders you will need to make sure they are in a published state.
1. Enter your course and click on Modules
2. Check the published status icon on the right of the module title bar. If it is unpublished you will see s grey circle with a line through it instead of a green check mark.
3. To publish just click on the grey circle icon.
Check your work: Enter Student Preview mode and verify that the module is visible.