L'Effrontee
French with English sub-titles.
This was the film that made the young Charlotte Gainsbourg a star in France, and rightly so. Her portrayal of a petulant fourteen year-old is one of the greats of French coming-of-age cinema, surpassed only by Adele Haenel's mind-blowing role as an autistic child in Les Diables.
Charlotte Gainsbourg went on to make many excellent (and some very controversial) films, both as child and adult actor, but L'Effrontee remains her piece de resistance.