More than 260 pupils from 26 schools attended yesterday's ukulele "jam" session at George Street Normal School, with another 280 expected today.
New Zealand cricketer Nathan McCullum made an appearance and joined the children in a rendition of John Fogerty's Proud Mary, rewritten just for him.
"Bowling, bowling, bowling down the middle," the children sang.
St Clair School teacher Alison Caldwell works with Music Education Otago, the team running the event.
She said these music-making sessions gave children and teachers the opportunity to learn to play an instrument together and were "a lot of fun for the kids".
"Music develops listening skills, reading skills and numeracy skills, but more than that, it's just fun, and brings communities together."
Ms Caldwell said ukuleles were an ideal instrument because they were easy to learn and anyone could play.
"Ukuleles are making a comeback," she said.
