Learn Italian: I ragazzi hanno corso per un'ora sulla pista di atletica. - The boys ran for an hour on the athletics track.

With verbs of motion like correre (to run), you use avere when focusing on the physical activity itself, especially when emphasizing a duration like per un'ora (for an hour). You only use essere when the running is directed toward a specific destination.

How would this sentence change if the boys ran to the track instead of on it?

If the track were the destination, the auxiliary verb would switch to essere, and the past participle would have to agree with the plural masculine subject (i ragazzi). The sentence would become: I ragazzi sono corsi alla pista di atletica.

Why is the preposition su (combined as sulla) used for the track instead of in?

In Italian, you run on the surface of a track, so you use su + la = sulla. Using a preposition like in (which would become nella) usually implies being physically inside an enclosed space or building, which doesn't fit the context of an open running track here.

Is it possible to say hanno corso un'ora without the preposition per?