Hilary Swank has praised Erin Gruwell, the passionate teacher she plays in new film Freedom Writers.

The movie tells the story of Gruwell's attempts to transform a group of poorly-performing schoolchildren into high-achievers in the 1990s.

"This is the story about the power of someone who believes in you and how that can change your life," Swank said. "My mum said you can do anything with your life if you work hard enough, but unfortunately I think a whole lot of kids don't get to hear that.

"And so when you have a person like Erin who can instil a belief then this makes an extraordinary story."