The teacher said she had to help troubled children who presented a range of problems or were neglected at home.
"They lie a lot," she said.
The teacher told the court she used to coach boys and girls in an extra-curricular activity.
She said she met the boy she's accused of offending against in 2012.
The court heard of arrangements made for sleepovers with the children at school on Friday nights.
The teacher said she never slept in the same bed as the boy, and never texted him either.
She claimed the boy lied to his peers in 2012 about sleeping with her, and his peers confronted her about it.
The teacher said she then reprimanded the boy.
"I told him it wasn't appropriate. I was a mother," she said.
"He apologised and told the other boys that he (was) lying. And I felt sorry for him and let it be, because I didn't want him to be bullied."
The teacher denied being in love with the boy.
She also rejected claims she gave the boy special treatment.
"I was concerned for all children equally."
The teacher said the boy was "emotionally fragile" but disputed the Crown prosecutor's suggestion this may have made the boy prone to manipulation.
She said the boy was "quite street-smart" and was himself "a manipulator of a lot of situations".
She denied being angry at the boy.
"I'm more upset at my position, at the fact that I'm actually here," she said from the witness box.
The trial continues.