Why did Jacob drop out of school?

Well, most of Eclipse took place over the summer.

As for Breaking Dawn, I have no idea, I didn't really pay attention, but I guess there was no mention of school, and he was always doing other things.

It diddnt dirently say that he dropped out , but we can just assume that if he did, then if tu were in his case , tu would too.
When tu transform into a supernatural creature with the circumstances of a vampire returning to hurt the ones tu amor then maybe school would not be your parte superior, arriba priority.
And also what cassie said, summer holidays and all that tiome inbetween.