The five-year-olds banging away enthusiastically on rows of electronic piano keyboards aren't making any noise; they're wearing earphones as big as their heads so only they can hear the music.
But these youngsters learning how to play the piano at the Wales Elementary School in the mid-western state of Wisconsin are sending shock waves through the educational establishment.
The students are part of a group that has shown remarkable improvement in mathematics after taking free twice-weekly piano lessons starting at the age of five. They have scored about 50 per cent higher on puzzle-solving tests than other children in the same school who did not receive instruction on the piano.
"The basic idea is that children are born with all of the neurons they'll ever have, but the connections between neurons are formed after birth, and it's those connections that determine intelligence," said Frances Rauscher, a University of Wisconsin professor of psychology who helped design the programme. Similar brain functions are employed in playing music and in doing maths, she said.
The findings come even as music continues to be cut from US public schools. While about 81 per cent of schools schedule regular music classes, only one in four students reports singing or playing a musical instrument once a week or more, according to the US Department of Education.
"It's not that not having music is going to hurt the kids, but what we have here is a proven tool," said Dr Rauscher. "To have this knowledge and not use it is to do a disservice to these children."
The pilot programme at the Wales Elementary School has been expanded with the help of grants from parents, businesses and the Yamaha Corporation, which makes electronic piano keyboards. Now, about half the school district's 4,200 students aged between four and 10 are taking piano lessons.