"There is a room in this school that no one knows about but me." 

This is the first line of the novel, and it refers to a tiny room in the attic of the school’s theater. Nobody knows about it because students have to go up a ladder, remove planks, and jump over an open space to get there. The room has a burned smell because it was rebuilt after a fire, but Julian eats his lunch in it anyway. Julian often hides here when he is skipping sessions with Dr. Whitlock. As Julian opens up more to Adam, midway through the novel, he eventually shows Adam the room, but only when Julian starts feeling comfortable around Adam's friends does he stop eating his lunch there.  

"How many stars?" 

This is a question that Julian's father always asked Julian when he was tucking him into bed at night. If Julian had a good day, he was supposed to say nine or ten are in the sky. If he had an especially good day, he was supposed to say “ten thousand stars.” When Julian has a wonderful time at Emerald's birthday party, dancing and drinking and being with Adam's friends, Julian makes Adam ask him this same question, afterwards. Julian answers that there are 10,000 stars in the sky.