Recon for burglary or home invasion would be my guess. They would have been driving through the neighbourhood scoping for empty houses or even had an eye on yours from the start, but none the less they would have been doing recon for the past couple of days.

After noticing there's never a car in the driveway between 730am and 6pm and you come home about 3pm (I assume that's what time school finishes). So after a while they think the stage is clear and try to break into the house. They more than likely saw you looking through the window, or had a suspicion you were there. But they didn't plan for you to be home at 1pm (which means they would have only been watching for the house for the past couple of days).

My guess is that they would either restrain you, threaten you to stay quiet or knock you out, then rob the place. But then they would have thought that if you were home you could alert the neighbors, parents, ring the police etc. They noticed that the police weren't rung immediately and they tried getting into the house one last time. Then realized its not worth it if there's a chance they could get caught and abandoned the plan then left.