Three boys who are now aged nine, ten and thirteen were kept under the care of Stephanie Chibnall, 45, after their mother had a breakdown in 2008.
But the actual tragedy for the boys started after the carer started beating them regularly with her fists, sticks and an electric fly swatter leaving them severely bruised and cuts.
The boys were punished for petty reasons such as not having any homework or not able to find Chibnall’s cigarettes.
The children’s books was found stained with blood but Chibnall lied to the teachers saying that the blood was from the injuries sustained due to pranks played by boys at their age.
A court heard how on one occasion she hit one of the boys with a bamboo stick so hard that it broke and finished her punishment with another implement. She once even made a boy brush his teeth with a toothbrush covered with dog mess.
During another episode, one of the boys was so badly injured his teachers thought he had been in a car crash. The offences, which left one of the brothers with a scar half an inch long on his forehead, took place between 2008 and March 2011.
The court heard her abuse eventually came to light after staff at the boys’ school grew concerned by the bruising on their bodies.
She was convicted by the Maidstone Crown Court following a trial though Chibnall, from Gravesend, Kent, denied three charges of cruelty to a person under 16.
Adjourning sentence until the end of October and granting bail, Judge David Griffith-Jones QC warned Chibnall she was likely to face a jail sentence.
Anthony Prosser, prosecuting, told how on one occasion, Chibnall phoned one of the boys’ schools asking for him to be excused from a Christmas play because he had fallen over and the bruising was causing him too much pain.
Mr Prosser told the court staff was aware he had fallen over the day before, which had been reported and logged. They spoke to him afterwards. They said he had large bruises on his left upper leg from hip to knee, looking as if he had been in a car crash. He said he had fallen over in the playground. Staff reported their concerns.
Mr Prosser added that the boys claimed they were beaten with sticks, slapped and punched to the head while living with Chibnall. Mr Prosser said specialist police officers spoke to the boys individually and one claimed Chibnall hit them with sticks, including one that had a small bit of metal on the end.
Under sentencing guidelines Chibnall faces up to nine years in prison for her three year reign of terror on the brothers.