The 14-year-old witness was answering questions by the prosecution and defence lawyers from behind a heavy green velvet curtain.
Elsewhere in the wood-panelled courtroom, the legal teams sat behind piles of documents and books.
The curtain was just one of the special measures that has been taken because this trial involves young people:
The young people can't be identified
The judge and lawyers don't wear their usual wigs and gowns
The boys who are accused sit with their parents or guardians, not in the "dock"
Some witnesses are giving evidence via a video link
Once during the hearing on Monday the judge told the lawyers: "It will be helpful if we take things very slowly."
He wanted everyone in the court to be sure about the things that were being said.
He also ordered that there would be regular breaks.