Education discount

Hi, i'm an high school student from Italy and i wish to but a 15 inch macbook pro without Retina display and as i was looking around i found out that there is an education discount.

I attend the second year of high school out of 5 before attending university but i'm not sure if this allows me to take the edu discount..

If yes does it apply also to USA store since i'm going there by August?
Shall i "buy" the Internation Student Identity CArd (ISIC) to show 'em i'm studying?e

Thanks in advanc