In sentencing submissions on Monday, the South Australian District Court heard the grooming by Bettina Schmoock could not be considered "mere fantasy", though no sexual activity ever took place.

"She took steps to act on that by booking a cottage where the sex was to occur," prosecutor Mark Norman said, as Schmoock shook her head and looked down.

"She persisted in encouraging the complainant to join her in the cottage, even when the messages showed he indicated his unwillingness."

In a victim impact statement read to the court, the boy - in the courtroom with his family - said his contact with Schmoock was initially comforting and described her as his best friend.

But he said their relationship became too toxic to maintain, leaving him feeling trapped and alone.

"I feel like becoming so close to a teacher... isolated me socially," he said.

"I feel a lot of shame about the events that took place."

Schmoock, who had taught at Concordia College, had earlier pleaded guilty to one aggravated count of communicating with the intent of procuring a child for sexual activity.

Defence counsel said she had been affected by a four-month-long hypomanic episode, as part of her undiagnosed bipolar disorder, at the time of the offending.

The mother of two is not an Australian citizen so could be deported should she receive a sentence of 12 months or more.

Judge Gordon Barrett continued Schmoock's bail and will sentence her next week.

Australian Associated Press