Hi there, you don't mention which version of Moodle you're using,
anyway i will assume you are using Moodle 1.7.1, if this is the case
- login as an admin.
- In the Administration block, click on the 'Gradebook' link.
- Uncheck 'administrators', and check the 'Students'
It is supposed to work this way.
I hope this helps you.
Omar Adam.
OEE Dev, Kuwait University