In 'Mean Girls' (2004), who plays Cady Heron?

In 'West Side Story', what are the two rival gangs? In 'The Outsiders' (1983), what are the two rival groups? Which 1986 film is about a teenager who skips school with friends Cameron and Sloane? Which 1985 film is about five students serving Saturday detention? In 'Clueless' (1995), who plays Cher Horowitz? In 'Legally Blonde', to which law school does Elle Woods go? In 'Good Will Hunting', at which university does Will work as a janitor? In 'Dead Poets Society', at which fictional school does John Keating teach?