Continuity mistake: When Sara is arguing with Derek in English class near the beginning, if you look closely at his name tag/student card, it flips from the front (with his picture) to the back (with nothing on it) several times between shots.
Continuity mistake: When Chenille and Sara are in the clinic with the baby and they argue, Sara leaves and Chenille is looking at her. There is a close-up of Sara about to walk out the door and in the background you can see Chenille staring off into space the other way, and then a split second later there is a close-up of Chenille and now she is looking at Sara again.
Continuity mistake: Sara goes to Chenille's the first time by walking under the "L". After Derek walks her home, he leaves in the opposite direction. After the ballet, Derek leaves again in the opposite direction.
Continuity mistake: When Sara first goes to school, she has to go through a security check. When she gives her bag to the security guard to be checked, the man opens all of the zips on the bag. The bag is then handed back to Sara, but when she puts the bag on her back, the zips are done up without her having time to do them up.
Continuity mistake: When Derek and Sara kiss each other in the flat of Sara's father, before they start to get naked, the point of view changes from behind Derek to behind Sara a couple of times. In one of the views, Derek's head is leaning to the right as he prepares to kiss Sara (and Sara's head is consequently also leaning to her right), and in the other point of view, is the other way around: both heads are leaning to the left as they approach for the kiss.
Continuity mistake: When Sara whips out her $20 bill and hands it to Snook, he takes it and has it in his hands. Then the $20 bill ends up in his hat without him even putting it there.
Continuity mistake: After Sarah's lesson with Derek in the classroom, in the following shots of them talking, Sarah's necklace sometimes under and sometimes over her sweater. Her movements are not enough to change its position like this.
Continuity mistake: When Derek is talking to Sarah during the audition, he puts his hand on her cheek. The position of his hand changes between shots; in the shots facing Sarah, some of his fingers are under her ear, in the shots from behind her, they're behind her ear.
Continuity mistake: Sara's bun changes places on her head during her last dance.
Continuity mistake: When Sara is talking on the phone to her friend from her other school, her friend asks if there are any white guys at her school, and Sara says no there aren't. In the classroom scene and in other shots, you can see a few white guys.
Answer: If you are talking about when they break up and ignore eachother at school, its 'Crazy' by Kacy and Jo Jo.