The teenager, a Moroccan citizen, had been charged with disturbing the peace by threatening crimes. Duesseldorf district court spokesman Marcel Due said a judge dropped the charges on Thursday on condition that he do 20 hours' community work and hand in the three-page, handwritten essay.
Due says the boy, whose name wasn't released in keeping with German privacy rules, said the incident in May was meant as a prank and denied having any Islamic extremist motivation. He told the court he found the fake grenade lying in the schoolyard.