A school day is from 8am to 4pm?

A school day is from 8am to 4pm? 

I disagree on this statement because we have our own rights to pick what time we start school and we have reasons and activities after school or before school. Firstly I don't want school to start at 8am and end at 4pm because many kids like me want to spend more time with our family. But when we get older we cannot spend any time with our family because we´ll move out and have our own family. Secondly I want to have longer basketball training because I like playing the sport and learning new techniques and drills. My second reason is because I need to be fit and exercise because my body can't cope with holding lots of weight and being healthy because I don't want any diseases or sickness. Lastly I don't want the teachers to have lots of work and I want them to spend time with their family and rest. Plus they need some time to themselves. We should keep it as it was in the beginning.