Authority of Schools

With incidents like this one in Mariemont where 17 students were suspended for drinking beer in Germany where their parents allowed it and were I was legal for them to drink. Why do some school officials feel they must control children, in this case older teenagers, at every step? They broke no law. The rules of schools do not super jurisdictions. Let parents rule their kids outside of school. This sounds like paranoia about alcohol. When did the temperance movement gain so much power in a city of beer drinkers?

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