I thank blindman and pootle flump for their kind help. Sorry for not mentioning that batch refers to the the actual period of study(For eg:2004-2008 or 2010-2012).
The test/exam I refer to is not that which is held on a particular date. It is actually a series of exams like Cycle Test I or Model Exam which is to be held for each subject. Anyway, the actual problem is that, I forgot to consider the dependency Class -> Test/Exam,Subject. Forget it if you're not able to get it. Anyway, I've got new problems and have to start working on it again.
Before I tell you the problem, I'd like to know where to post my questions and who moved my message here(Is it automated?!!). If I'm creating problems posting my problems in the wrong place, please do move it this one last time alone after which I will learn more about the layout of this community!
Also, how do I show tables(The one I had shown was terribly aligned due to automatic annihilation of a group of spaces to a single space when it gets posted!)
Now to my next problem:-
I've got this dependency, Department -> HOD(Head-Of-Department). But what do I do in case of change in the HOD of a department? Should I consider this dependency at all? Or is it better that the old HOD is overwritten by the new HOD? Same goes for class teacher. But this method reduces the usability of the software since we can't view which HOD a particular batch was under.