Student Online Testing

I have a client who has implemented employee training within Drupal and has had much success in showing who has accessed what pages... Now he has asked me to develop an automated testing process. I envision building a tool that will allow him to create tests for each class within a Course. Is there a recommended way using modules that will allow me to create an environment where he can create on-line tests per class? The student would take these tests online and he wants to give them immediate feedback on-line after it is submitted.

Thanks for your ideas!