Here is a typical school day for Sabrina, who is a tenth grader: Wake up at 6:00 to arrive at school by 7:00 for orchestra practice. Attend classes from 8:00 to 3:00, changing classes every hour. After school, go to choir practice and then to either dance lessons or a part-time job, depending on the day. Fill in any free time before dinner (which is usually around 8:00) watching television or talking on the phone. After dinner, complete several hours of homework and engage in instant-messaging on the Internet with friends. Be in bed by midnight. Is this schedule consistent with good physical health