WHEN I interviewed actor Eric Roberts some years ago, he spoke with a stammer that was not evident in any of his films. He explained that the characters he played did not stammer and that he started acting as a form of speech therapy.

I was reminded of that conversation while watching Rocket Science, in which the central character, Hal Hefner, is a New Jersey high-school student with such a pronounced stammer that he has a hard time ordering lunch in the school cafeteria.

Endearingly played by Reece Daniel Thompson, Hal has other problems, witnessing the marital break-up of his parents and living with an aggressive older brother (Vincent Piazza). As Hal struggles to deal with his adolescent sexuality, he is surprised when Ginny (Anna Kendrick), a bright, attractive and supremely confident student, invites him to become her partner on the school debating team. Her former partner (Nicholas d'Agosto) dried up during the state championship debate and now works in dry cleaning.

Teen angst suffuses Rocket Science, the first narrative feature from Jeffrey Blitz, the director of the compelling Oscar-nominated documentary Spellbound, which also dealt with verbal gymnastics and highly competitive youngsters as it followed the finalists in the US national spelling bee. In Rocket Science's debating scenes, the students make their points in tightly scripted speeches and with dazzling rapid-fire delivery.

Blitz, who stuttered in his youth, evidently empathises with his protagonist in this calculatedly quirky US indie. It earned him the award for best director at this year's Sundance festival. While some of its oddball details feel contrived and excessive, Rocket Science is refreshingly unconventional in its treatment and reliably inventive as it adeptly sidesteps the potential cliches of the coming-of-age genre. MICHAEL DWYER