The teacher, who cannot be legally identified, is on trial in the Downing Centre District Court over alleged unlawful sexual activity with the student who turned 17 years old in 1984.
Crown prosecutor David Patch told the court that the student, who also cannot be named, started at the school that year and was soon moved into the teacher's maths class.
The teacher was about seven years older than the pupil at the time.
"It's the crown case that the accused was sexually interested in the complainant from when they first met and almost immediately began grooming the complainant," Mr Patch said.
As part of the process of grooming, the teacher also set about forming a close relationship with her mother, the jury was told.
Within a week of meeting her, the accused started asking personal questions in private about the girl's family and a short time after that, suggested picking her up from her home and taking her to school.
The teacher took the pupil out to dinner in Sydney's inner west in March 1984 when they kissed for the first time in a car, the court was told.
"The complainant did not like this but did not know what to do," Mr Patch said.
The accused's conduct then escalated to touching her breasts which made the girl scared, jurors heard.
During a trip to a national park north of Sydney around Easter of 1984, the teacher allegedly had sexual intercourse with the student.
"Throughout this incident she remained frozen and she didn't touch or talk to the accused at all," Mr Patch said.
"She felt trapped. The complainant didn't know how to say that she didn't want to have sex."
It is this single charge of carnal knowledge which the teacher is on trial for and which they have pleaded not guilty to.
The court heard a key issue in the case is whether the student was under or over 17 years old when the sexual activity took place.
Crown prosecutors have to prove beyond reasonable doubt that the girl was under 17 for a guilty verdict to be reached.
The teacher and student are alleged to have had sexual intercourse around 10 times before August 1984.
She was told to keep the alleged unlawful sexual activity a secret or she would be expelled, jurors were told.
At the urging of the teacher, the girl left her studies.
"She felt she had no choice as the accused pushed her to leave," Mr Patch said.
They eventually entered into a long-term relationship.
After separating in the 2010s, the alleged victim went to police in March 2021, leading to his arrest over a year later.
In a phone call recorded by police in 2021, the then ex-teacher said they had cared about the woman from "day one".
After being asked whether what they did was wrong, they allegedly described it as a "matter of definition".
"It's a matter of perspective. Anything that's about kindness can't be all that wrong," the teacher is alleged to have said.
Defence barrister Wayne Flynn gave brief opening submissions asking the jury to keep an open mind.
"I'm asking you to please keep an open mind until you've heard all of the evidence," he said.
The trial will continue in front of Judge Sophia Beckett on Tuesday when the complainant will give evidence.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
Kids Helpline 1800 55 1800 (for people aged 5 to 25)
21°C