Ms Cooper said it was not unusual for wild ducks to nest in trees or on a ledge or balcony.
Due to ducklings being born with fluffy down feathers, they are normally protected when they leave the nest but this was an “exceptionally high place for them to hatch”, the RSPCA said.
School staff helped by containing the ducklings in a bucket before RSPCA officers arrived on scene.
After the RSPCA moved the brood to the front lawn and played duckling noises on a phone, the mother finally appeared.
“I was beginning to think she might not return,” said Ms Cooper.
“I laid the bucket on its side and it was a great sight watching her call them and the little ones emerging from it and running towards her.
“The school has lovely grounds, so hopefully she’ll be able to keep them all safe.
“Every kind of animal deserves a helping hand and we can achieve so much more when we work together.”
The school said it was not the first time a duck had nested on their roof and they were very grateful for the charity’s help.