Having to be at school by 7:30 or 7:00 in the morning eventually turns teens and kids into zombies, and not in a good way. Most days, kids, especially teens, come home with loads of homework, causing them to go to bed late, leaving then with only a few hours of sleep. Early times such as these can also cause stress, which can lead to loss of sleep too. This means that kids and teens still have to get up early in the morning, and sit through hours of learning with only a few hours of sleep. This can be extremely harmful to the teens health and grades. With this being said, later times such as 8:00, 8:30, or maybe even 9:00 would be a better option considering the health and grades of teens and kids.
I hope this helped! :-)