Most American adults wake up around 5:00 AM to 6:30 AM for workdays and some sleep later on weekends when they have no work to do.
Me I wake up at 7:00 AM everyday but sometimes I will sleep in until 10:00 AM if it's not a workday for me.
Some kids have to wake up at 6:00 AM to get ready for school so they have time to shower, eat breakfast and get ready to board the school bus.
The school bus in my area comes around to pick up the students around 7:00 AM in the morning so the kids must be up and ready in time to catch the school bus by 7:00 AM even though the school day doesn't actually start until 8:00 AM.
But the bust has to come out here to the smaller town and pick up students which takes them time so they must pick the kids up by 7:00 AM so they have time to reach the school before 8:00 AM.