What time do you have to go to high school?

The hours at high schools vary. Some are more traditional, with classes from around 7.30 AM till around 3.30 PM. But some schools are run like a college campus, and students have certain longer days with many classes, and certain shorter days with fewer classes and time for extra-curricular activities.

Generally, in high school, you are changing classes and changing teachers, but typically, you are there all day. However, some vocational high schools have release-time for students who are learning a trade, so these students might be in the classroom in the morning and then at the job site in the afternoon.