Max Mashal, a sixth grader, used his iPad at Pinnacle Peak Elementary School in Scottsdale, Ariz.Credit...Joshua Lott for The New York Times ROSLYN HEIGHTS, N.Y. � As students returned to class this week, some were carrying brand-new Apple iPads in their backpacks, given not by their parents but by their schools. A growing number of schools across the nation are embracing the iPad as the latest to