Vickrum Digwa was recorded in a police van discussing Henry Nowak's murder in Southampton.
The mother of Harvey Willgoose says some schools do not wish to be part of an anti-knife crime tour.
The group says the vehicle, which includes a knife amnesty bin, will be used to run workshops.
The Knife Angel, made of more than 100,000 confiscated blades, helped inspire the exhibition.
The boy says he and his friends were bringing "random household objects" into school for a game.
The boy, who cannot be identified, denies attempted murder, wounding with intent, and unlawful wounding.
A man charged with a serious knife attack in north Belfast has been told by a judge that he faces serious charges and that he should seek legal representation.
The Scottish Police Federation is calling for stronger search powers to prevent young people from carrying knives.
