People don't like the idea that some kids may be born smarter than others. That they inherently have more intellectual potential.
More than just "not like" the idea, some dismiss it altogether as nonsense.
Yet, no one could watch the Chicago marathon yesterday and believe that, for whatever reason, Kenyon and Ethiopian genetics are not a distinct advantage in running marathon lengths at a sprinter's pace.
Some kids in your class are Kenyans. They are genetically designed to run intellectual marathons. This doesn't mean expecting less out of your other kids. It means expecting more out of some.