A Folder resource should be available to students by default. I would check the following:
- Click the folder settings edit (update) icon, or just click the folder link.
- While you are on the edit page, go to the Settings...Folder Administration block (usually on the left side), and click the Permissions link.
- In the Permissions list, View Folder content should include Authenticated User, or Student. If not, add that role to the View Folder permissions list.