Question for Teachers

[imported_CaseClosed326]

I am currently is college trying to become a history teacher, during my last session with my advisor he told me something that was pretty confusing. He said something along the lines of 'you have to teach only to the upper portion and middle portion of your class, don't worry yourself about the bottom section of kids, there is nothing you can do. Do that and you will be able to get by as a teacher.'

Ok, so anyone here who teaches, can you tell me if this is how it really is? When I get a job will I have to just give up on a section on my class? This seems like giving up or am I just being naive?