In the land of earthquakes, even IKEA has kits to bolt heavy indoor furniture to the walls just in case. Turns out, securing heavy furniture — in this case, a piano — outdoors on a school playground might also be a smart idea.

The parents of a 9-year-old student are suing the Menlo Park City School District for injuries they say she sustained when a piano on the outdoor playground of Oak Knoll Elementary School toppled over on her as another student jumped on top of it, according to court documents.

The lawsuit, filed in San Mateo County Superior Court on March 18, alleges that the girl is expected to have "some permanent disability" as a result of the accident. The school should have known that an unrestrained piano with wheels could easily be moved by students, the complaint states, and "that injury was likely to occur frequently in the absence of adequate supervision."

The Ahn family's attorney, Forrest Shryock, said the parents are very concerned not only for their daughter, but also the other students on campus. "Playground supervision is a big issue in California now, with tight budgets leading to limited supervision. This (case ) kind of fits into that whole issue," he said. "You'd think that if someone saw pianos being pushed around, and kids climbing on them, they would have stopped it."

He said that he's been told the piano is now secured to a fence.

According to the school district, it received notice of the lawsuit on Thursday, April 4, and couldn't comment on any specifics at this time.

"This was an unfortunate accident, and we regret any injuries this child sustained," Superintendent Maurice Ghysels told the Almanac. He said the piano was moved to the playground "as part of a trend to place street pianos in public places to encourage interest in music by students. We had an extra piano at our school and after hearing of the success of this practice in San Jose, we placed the piano so it was available to students during recess. It was very well received by students and parents."

The court has scheduled a case management conference for May 23.