I'm trying to display some data, let me describe it to you.

I have a group of about 5000 teachers. For each teacher, I have the rate of passing students (calculated by the total number of passes / total number trials) over a years period. For each teacher, I have the associated specialties (teachables): Math, Biological sciences, social sciences, etc. Lastly for each teacher, I have the amount of students they've had over a 3 year period (we call this quantity "Volume"). What I would like to show is the relationship between Passing Rate and Volume, by Teaching Type.

It was suggested I try a funnel plot. Does this seem appropriate? Any other suggestions? Thanks