Bed Times and Wake up times
In a whole day, there is 24 hours. You need about 8 hours of that day sleeping. If you have to be in school 8:15 then you would probably wake up at about 6:45-7:00 maybe earlier. This leaves you to sleep at least 11:00 or 10:00 or even more early. The earlier the better. You should sleep at around 9:00 which is better. If it is a weekday, you should wake up depending on when your school starts. If it starts at 8:15 then you should wake up at least 1 hour earlier. What you should wake up at is probably either 7:00 or 6:45. If it is a weekend you can sleep longer but not too long. You should wake up at 9:00, 10:00 or eleven at the most. Some people wake up earlier which is fine also.