The woman in her late 20s was sentenced to six-and-half years' jail in Queensland after pleading guilty to seven charges, including maintaining a sexual relationship with a child.
The boy's mother was unaware of the relationship and thought her son was spending time with the teacher's intellectually impaired brother.
The court said the teacher seduced the intellectually impaired student in 2011.
The woman now banned from teaching warned the student not to tell anyone or she would go to jail. The woman was arrested in January 2014.