I'd like to do something like English, a Teacher is in a town

They also can have qualifications (from none to lots). How do I do
I mean I can see a Teacher could have a QualificationID field which
could have could contain numbers like 3,4,6 (meaning they have
qualifications of X, Y and Z). How do I do it in rails associations?

sounds like you need a has many through (or has and belongs to many)
between teachers and qualifications, since I assume that many teachers
may have the same qualification. This join model could also hold data
like when the qualification was awarded etc.