Schools were made because children needed the proper education during the times they were used for hard labor, like working in a factory or polishing shoes.
Actually, the first schools for the rich, and only for boys, were made primarily for education for them to then be capable of working industrialy or owning land.
Hard Labor and the such wasn't the real reason that schooling was made for, as those who would end up doing such wouldn't be rich and wouldn't require an education. You don't really need an education to do Hard Labor, beyond being able to do what you're told and some common sense.
Although anyways, now-a-days schooling is to set you up to be a part of the national community, and to be able to work. The ability to make friends at a school is also purposeful as it teaches you social skills, which are also useful in later life in the community.
More-On-Topic: They block Facebook at school because it's not needed. When you go and use computers at your school, they're there to be used for teaching and learning, not so you can send messages to people and play 'Farmville'. :/
Also, I've no doubt that by using Facebook you can find things that the school would rather have cencored.
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