Parents of young children in Merseyside are being taught the dying art of the nursery rhyme - by the Royal Liverpool Philharmonic Orchestra.
Children taking part also get a chance to bang some instruments
Musicians have been visiting nurseries in four areas after an initial 12-week pilot in St Helens, which organisers described as "incredibly popular".
Now parents in Liverpool, Wirral and Knowsley are queuing up to learn the classics alongside their children.
The sessions are said to improve speech development and parent-child bonding.
Judith Agnew, the orchestra's education and participation manager, said the programme was developed as a way of involving parents in sessions they ran in nurseries.
"We have been phenomenally surprised by how successful it has been," she said.
"As the parents go home and talk to their friends, the sessions are just getting bigger and bigger.
"In some sessions now we've had to put a limit on the number of parents we can let through the doors because we physically can't fit any more people in."
Sure Start nurseries in Toxteth, Liverpool, Leasowe in Wirral and Kirkby and Whiston in Knowsley are currently running programmes.
Three or four musicians visit each nursery for weekly hour-long sessions, teaching classics alongside lesser-known rhymes such as "Fingers Like to Wiggle, Waggle" and "Little Johnny Dances".
The programmes are funded by the Youth Music initiative, a lottery-funded charity which aims to provide music making opportunities for children in disadvantaged areas.
Additional money has also been provided by the Paul Hamlyn Foundation.
One mother who brings her 18-month-old girl, Aliyah, told BBC Radio Four the sessions in Toxteth had helped her development.
"When she first came here she was very shy. But after 12 weeks she is so confident, full of life, singing all the time - singing all day. She wakes up singing," she said.
Although parents and children get a lot from the sessions, Ms Agnew said the musicians were also seeing benefits.
"There is an intimate communication with the audience that they just don't get on a concert platform," she said.