In British people^x, Prepositions^x

Tuongvan wrote:Bill has been UK on/ US at the same grade for several years now . Perhaps British people use on and American people use at . Or this sentence has other meaning ? I 'm very confused now.Hi Van,The dictionary is correct about the difference between AmE and BrE regarding the usage...

So it is a matter of where you originate? What about Americans? Is there a difference between them and British people? My teacher marked it as wrong when I wrote it without the preposition, but maybe he was wrong then.