There are several ways to do...
1.
(If Your file system is NTFS)
Create a guest account for your students.
In Your
administrator account, First open the
explorer and select the files which are to be protected. Right click and go to properties and click
advanced. There check the option
Encrypt Contents to Secure Data.
Now, the users using the guest account will never be able to see the contents of files. They cant even delete them.
2. Suppose, you need to completely hide the folder, then follow this thread
*www.thinkdigit.com/forum/showthread.php?t=36542
3. Use a software like
folder guard in which you can find all the options like Read only, Hidden, Lock etc..
www.winability.com/folderguard/