Waterloo Road was filmed at the former Hill Top primary in Kirkholt, Lancashire, which has since merged with a nearby primary, between October and December last year.
More than 100 Year 9 and 10 pupils from Springhill high in Rochdale were drafted in as extras for eight days of filming.
Kiran Hameed, 15, was cast as one of the bad kids and told to wear her costume uniform as scruffily as possible.
"We didn't really get a chance to talk to the stars," she said. "But we saw them and they had so much make-up caked on they looked bright yellow. We just did our own make-up in the costume room."
Aspiring actor Suleman Malik, 15, took the opportunity to learn from the professionals - and from their mistakes.
In one scene with Angela Griffin he said: "They had to do a lot of takes because she kept forgetting her lines."
Charlene Mellor, 14, added: "There was a lot of hanging around but it was fun. The main acting we had to do was just sitting around trying not to look at the cameras."
Waterloo Road is produced by Shed Productions, makers of Footballers'
Wives. It stars Jill Halfpenny, who played Kate in EastEnders and also took part in the BBC's Strictly Come Dancing, and Denise Welsh, former landlady of the Rovers Return in Coronation Street.