A former Fleurieu Peninsula teacher who pleaded guilty to Maintaining an Unlawful Sexual Relationship with a child is awaiting his next court appearance.

Matthew John Freeborn appeared in the Adelaide Magistrate's Court on Friday 30 October and pleaded guilty to maintaining the relationship with the child between May and December in 2016.

According to an ABC report, Mr Freeborn’s guilty plea was entered on the last day a 40 per cent sentencing discount was available to offenders who plead guilty within four weeks of being charged, ahead of a law change.

Mr Freeborn’s next hearing is his Arraignment at the District Court on December 18.

He was previously on staff at Investigator College’s senior and middle schools on the Fleurieu Peninsula as the Director of Music.