As more than a million New York City public school students returned to class yesterday, Maria A. Aviles, the principal of Junior High School 45 in East Harlem, greeted children and reassured parents – a familiar opening-day ritual for a year that promises broad changes for the nation’s largest school system and its principals. (…) At Khalil Gibran, where the founding principal resigned before school began after trying to defend the word intifada on a T-shirt, the school’s supporters held a banner reading New Yorkers Support the Khalil Gibran School, and set up a table loaded with hummus, pitas and apple juice. The school is a vision of tolerance, said Rabbi Michael Feinberg of the Greater New York Labor-Religion Coalition. After dismissal, Adnane Rhoulam, 12, said he and other students had learned to count to three in Arabic and to say hello three different ways. Adnane, whose mother is from Morocco, said he hoped to understand more about what my mom’s talking about.