I am a high school student her is my top ten:

Amelie (2001)  
Hana-bi (1997)   
The Bicycle Thief (1948)   
Battle Royale (2000)  
The Road Home (2001)  
Fanny and Alexander (1982)  
Hard Boiled (1991)
Seven Samurai (1954)
Aguirre, Wrath of God (1972)
The Seventh Seal

Not that all of these are good for all high schoolers some like Fanny & Alekander would be to slow for mos teenagers.