The departure of half the core teaching staff at an elite Upper West Side elementary school has roiled parents who worry test prep is destroying the school’s creative spirit.

In July, close to half of the parents at the Special Music School signed a letter decrying the “apparent shift in school culture” and the new principal’s leadership.

 “This is not the same place it was three years ago,” said a 3rd-grade parent, who like most interviewed, asked to remain anonymous for fear of negative repercussions for their children. “There’s a lot of talk about data and test prep, and I didn’t used to hear that.”

The school, which until recently was a program at PS 199, provides an almost private-school like experience for musically gifted students who must audition in kindergarten and again in 5th grade for middle school.

“It’s been a slow erosion, from Technicolor to black and white,” said an upper grade parent. “We had a very rich environment, and we’ve been reduced to the DOE mandates and the Common Core standards. But the joy in learning and the creative element – I don’t see it any more.”

For example, the disgruntled parents say, an annual trip to Ellis Island as part of an immigration lesson was cancelled because it was not part of the city-sanctioned curriculum.

And even though on average 95% of students have consistently passed state exams, parents say 3rd grade students spent two months on test prep last year, compared with two weeks in past years.

“The issue here is, if it ain’t broke, who’s trying to fix it and why?” said Aaron Pallas, a sociologist who studies education at Columbia University’s Teachers College.

The debate over whether the Education Department, in conjunction with the federal No Child Left Behind law, has harmed or helped city schools with its data-driven mandates and focus on standardized test scores has been heated since Mayor Bloomberg took over the schools a decade ago.

“There is a real possibility that responding to these very powerful mandates has resulted in shifting teacher’s practice,” said Pallas, “away from instruction that may have been more student-centered and creative and that allowed children to follow their own path of inquiry.”

School leaders, however, say the changes have improved the school and that the turmoil was inevitable part of becoming an independent school.

 “Katie [Principal Katherine Banucci-Smith] made a lot of changes I thought were good for the school,” said PTA co-president Yvonne Lau, “but not everybody thought so.”

Principal Katherine Banucci-Smith believes that any lingering dissent is the work of a small faction of parents, and she chalks up teachers’ departure to budget cuts and voluntary transfers.  She said the letter signed by parents was the result of “a lot of gossip and hysteria.”

She added that for years there were no teacher evaluations and that every year some students fell through the cracks needlessly.

“The kids are happy, engaged, articulate,” said the former River East elementary school assistant principal and testing coordinator. “All that I’ve tried to do is to add more cohesiveness.”