Josh said it was "really nice" of his classmates to do that for him. He had been sad to lose his guitar.
"I had just started lessons and I was really enjoying it," he said.
Mum Fiona Brown said the busking plan was incredible.
The school had done a great job of making life as normal as possible for her three kids in a "shit situation", she said.
Mr McLean said the Browns were an awesome family.
"We're happy to go the extra mile for them because they do so much for the school."
Busking kids
Day: Friday
Time: 12pm-2pm
Place: Outside Paper Plus in Bethlehem town centre
Who: Room 6, Otumoetai Primary School