Community service is good for students from an early age. It teaches them how to cooperate with others and the benefits of hard work. The work load, Most definitely, Should not be much. It will be easy for students to accumulate 10 hours all throughout their four years of high school. This will teach them better time management skills that will prepare them for college and beyond.
Volunteering has two main virtues--the act and the effects. Forcing teens to volunteer negates the former virtue. Part of the benefit of volunteering is the satisfaction of having helped others VOLUNTARILY. By being compelled to volunteer, The meaning behind the act is lost, Even if the results are the same. It's like being forced to donate to charity at your workplace--the money helps the charity regardless, But the spirit of charity is not there. Making teens do volunteer work to graduate devalues the act of volunteering and has not been shown to make students more likely to volunteer in the future.
Almost every student I've seen will do the required hours and then never volunteer again. Do we really want teen's only memory of helping out in the community to be something that was forced on them? Also, Requiring hours takes away from students' ability do homework and to get summer/weekend jobs. Most able-to-work students I've talked to say they would like to get a job but can't because they still need to do their mandatory "volunteer" hours.
Volunteering should not be required to graduate high school because it makes teens lose family time and it also makes them have to do things they don't need to do. Instead of worrying about volunteering they should be worrying about college and their homework and actually learning not being focused on community service