<p>At the graduate level these are typically done with the faculty thesis or dissertation supervisor you are assigned during the admission process. Undergraduate tutorials are conducted within the colleges. They are different in frequency but my point was mainly that the tutorial/supervision culture that drives the undergraduate teaching process at Oxford and Cambridge permeates the rest of the teaching and research culture even at the graduate level. But also remember that your original question had to do with comparing Oxbridge to places like Harvard and Yale. H & Y will also, at the graduate level, assign graduate supervisors so there isn’t any reason to fear getting a poor education at those outstanding institutions. If your son’s choice is betwee Oxford, Cambridge, Harvard, and Yale, then he truly has little to worry about IMO.</p>