A primary school teacher who wanted to have sex with her 10-year-old student, and had his name tattooed on her chest, has walked free from court.

County Court judge Mark Taft said he was at a complete loss to understand why mother of eight Diane Brimble, 47, had engaged in "such utterly inappropriate conduct which must dismay every parent".

"You breached the trust reposed in you by [the boy's] parents who properly expected that a classroom teacher would care for their son in a professional manner," Judge Taft said on Thursday when sentencing Brimble on a two-year community correction order and 200 hours of unpaid community work.

Brimble will be placed on the sex offenders register for eight years, be assessed and treated for any mental health condition, take part in offender treatment programs and has lost her career as a teacher.

"The scale of your obsessive behaviour was demonstrated by your tattooing [the boy's] name on your chest with an infinity symbol, your endeavours to move your own children into the primary school where [the boy] had transferred and the letters that you penned which spoke of your undying love for him," Judge Taft said.