Not even a faint buzzing could be heard in the tense Düsseldorf courtroom as the trial began punctually at 11:30am on Tuesday.

The accused betrayed no sign of emotion as court officials read him the charge – serious bodily harm for recklessly popping a paper bag too close to the teacher’s head.

The incident arose in the lunch break of what many thought was going to be just another normal day at the Düsseldorf high school – a school like many thousands of others in Germany.

The 53-year-old teacher asked the child to throw his paper bag – which is believed to have previously contained a bread roll, possibly with cheese or ham – into a bin, rather than littering the school yard.

According to a report in Bild newspaper, the boy then replied, “But first I’m going to bang it.”

“Don’t do that,” implored the teacher in response. “It can cause hearing damage.”

But not to be deterred from his mischievous plan, the boy orally inflated the now-obsolete sandwich wrapper, and burst it before the teacher had time to cover her ears. She then called the police.

The central issue at the trial, which thus far divides Germany’s top legal commentators, remains the distance between the bag and the teacher’s ear at the time of its fateful pop.

The teacher claimed the pupil snuck up behind her and held it directly to her ear, but the boy offered a different account. “The teacher was at least five metres away when the bag burst,” he insisted under oath.

Three fellow pupils, who witnessed the incident, have confirmed the boy’s story. They added that he apologized to the teacher, though she did not accept his contrition.

The judge dismissed the teacher’s claim.

The Local/bk