What is the role of a teacher to intelligent students?
A challenger, mostly. The Teacher is the content expert, and the intelligent student catches the material easier than those in the "middle of the bell-shaped curve." So, the teacher is at a crossroads: leave the student to their own devices, or come up with differentiated instruction that will challenge the intellect.
Many teachers find intelligent students harder to teach than those at the other end of the spectrum... simply because the smarter ones challenge the curriculum, demand higher level analysis of the content, and want to engage their brainpans through debate and discussion.
While this discussion can be an intellectual feast for the smart kids and teachers... it has the tragic effect of potentially leaving the rest of the class behind, disintersted due to their inability to process at that level, and then the teacher has lost the class.
Teaching is a fine line between reaching all of the students, and just a few.