A young female arts teacher who took her students on trips to the beach faces 20 years behind bars after pleading guilty to 48 sex offences against two female pupils.

The Weekend West can today reveal sordid details of the case that has rocked the education system after the 28-year-old admitted the offences.

The teacher carried out the lesbian relationships with the students at a southern suburbs school over two years.

The woman, who cannot be named to protect the identities of her victims, lost her job after she was arrested last year and has now been put on an Education Department blacklist.

This week she pleaded guilty to a string of sexual offences against the teenagers, with charges relating to a third girl dropped by prosecutors.

But authorities say the sordid scenario led them to bring a charge of persistent sexual conduct with a child under 16, which carries with it a possible maximum sentence of 20 years jail. The teacher admitted that charge, and dozens of others.

It is understood she had only been teaching in WA since 2013.

Newsletters from the teacher’s former school reveal trips to the beach and forest were a core part of her role.

She also wrote about hosting photography and graphic design workshops.

But it was her activities with students outside the school gates which saw WA Police launch an investigation in the middle of last year, after a girl made allegations to the school she had previously been “in a relationship” with the teacher.

Rockingham Magistrate’s Court was told the first victim was aged between 16 and just 13 at the time of the offences against her.

Over 16 months, the woman indecently dealt with that victim nine times — and also sexually penetrated her 10 times. They included repeated assaults on Australia Day 2016.

It was that victim with whom prosecutors alleged the teacher persistently engaged in sexual conduct.

A second student, who was over 16 at the time of the offending, was indecently dealt with and sexually penetrated 14 times in 2017.

Some 23 further charges, relating to an alleged third victim, were all dropped by police.

But in a statement, they said those allegations would still make up the complete picture to be put before the courts.

“Police prosecutors in conjunction with the investigating officer reviewed the evidence ... and made a decision to amend numerous charges, as well as discontinue several charges,” they said.

“The facts of the discontinued charges are being used to support the most serious charge of persistent sexual conduct of a child under 16, which carries a punishment of 20 years.”

She was arrested in July last year.

“The teacher was dismissed by the Department of Education shortly after,” Mike Cullen, acting executive director professional standards and conduct, told The Weekend West.

The woman’s lawyer requested a psychological report and a pre-sentence report ahead of a sentencing hearing in May.