Last year, before Anthony Boccia joined the teaching staff at Valley High School, his students spent hours in a windowless room in the company of John Travolta and Olivia Newton-John. Overseen by a long-term substitute teacher, the group of eight children, who are mostly non-verbal and physically and intellectually disabled, watched Grease and a drawer-full of other well-worn VHS tapes, often from the first bell to the last.