Dag Voigt, the headmaster of Bjerkreim School in Rogaland, south of Stavanger, decided to experiment with the balls with two classes back in 2005 after a local physiotherapist Tore Jakobsen came to him with the idea.
According to a documentary on the initiative, Ball versus Chair, the children quickly developed better core muscles and stronger backs, without any adverse impact on their studies.
The school now uses balls instead of chairs for all pupils between the ages of 10 and 13, arguing that as the balls are actually cheaper than chairs, it is not a major additional cost.
interviewed for the documentary, Jakobsen said that the benefits appear to come simply from increasing the movement children made during lessons.
“It's to get more movement into the every day in school — that's basically the thought,” he said. “The more movement children get into their day the better, but none of this has been scientifically proven.”
Ball vs Chair (Ball vs Stol) was made by the Oslo-based film company Heisholt Inc, and has been broadcast on the website of the Aftenposten newspaper.
Terese Aalborg, the film's director, said that she had had the idea when she was researching ways to improve school for her own daughter, who found it hard sitting still in the classroom.
She said pupils at the school had all said they liked having balls in the classroom.
"Everyone I talked to loved it: they wouldn't go back to sitting on chairs," she said. "A ball is softer, a chair is very hard, it's very static and you can't move very easily. They could see that they were getting stronger. They could really feel the difference."