Hundreds of children and parents were pleasantly surprised when their school teachers and administration serenaded them with the hit song "Let it Go" from Disney's "Frozen."

The playful moment was caught on video, and occurred at Baden-Powell and St. Peter's Church of England Junior School in Poole, Dorset.

Headteacher Paul Howieson said that the staff practised diligently for the surprise performance.

"We have been working on the performance for the last three weeks and did two or three rehearsals in the church and several at school," he told The Mirror. "We had to close the curtains and pretend nothing was going on but it worked. I don't think anybody had any idea what we were up to."

About 750 children and their parents were gathered in the church for a Christmas celebration, and couldn't believe it when Howieson began reciting the song's lyrics.

"I read the first verse and the kids started to stir by the third word and by the time I got to the line 'looks like I'm the queen' they were laughing," he recounted. "Their reaction was extraordinary.

"I think it's good for them to see their teachers in a different way, and see we like a laugh as much as anyone. And it was great to get Reverend Michael involved too. It's a really positive association with the church for the kids."

Reverend Michael Camp and about 100 staff members belted out the catchy song.

"We're a big school so getting everyone together for a rehearsal was not very easy but we did it and we managed to keep it a secret," Howieson said.

"All the parents said how great they thought it was. The problem now is finding a way to go even bigger next year and keep it a secret."