Both DS and DD were nominated by their teachers. DS' teacher had taught him for over a year because he was subject accelerated into her classroom the previous year plus she had taught his 3rd grade GT classroom for decades. DD's teacher also taught for decades and would praise her to her other classes and teachers in the department and posted her work products in prominent places. The bottom line is find someone who thinks your child is exceptional and can reasonably be expected to know based on exposure to many students of the same age. At the same time, don't worry too much about finding the perfect Nominator as long as your DD has the numbers.