Aaron James Wormald was the head teacher of creative and performing arts at Jamison High School in South Penrith before he was suspended and eventually arrested by police in June 2022.
Raiding his home in the Blue Mountains town of Winmalee, officers seized three electronic devices containing thousands of naked or explicit images and videos of children.
The 48-year-old was sentenced at Sydney's Downing Centre District Court on Thursday over the child abuse material as well as abusing three of his students.
Wormald sexually touched two female students in plain sight of witnesses and assaulted a third by grabbing her by the shoulders.
The head teacher was seen around school talking to female students about their partner's genitalia and hentai.
He posed as teenagers online, creating a number of fake Snapchat and Instagram profiles, to chat with young children and manipulate them for explicit images and video clips.
"Let daddy see one more (picture)," he told one teenage girl.
More than 15,000 images were found stored at his home as well as almost 2500 video clips.
Judge Graham Turnbull said the material found at Wormald's home was confronting.
The judge criticised the teacher's inappropriate and sexualised messages to real children to deceive them into taking explicit pictures for him.
"What he was doing was cruel and harmful at an emotional level," he said on Thursday.
There would also be the ongoing shame the child victims felt as they knew material they had sent remained online, Judge Turnbull said.
"The presence of such images in the hands of a man like this … creates a sense of foreboding and enhanced distress," he said.
He described the then teacher's behaviour to a year 7 student in touching her in an exaggerated sexualised manner "abhorrent".
The judge sentenced Wormald to a maximum of 11 years and eight months behind bars with a non-parole period of seven years and three months.
The ex-teacher wore prison greens and watched by video-link from Junee prison.
Judge Turnbull noted the onerous conditions that Wormald had faced in custody, including being beaten up, sexually assaulted, locked in his room and having his genitals crushed.
The court took into account Wormald's diagnosed mental conditions including bipolar disorder, hypomania and depression as well as post-traumatic stress disorder from his sexual abuse as a child.
Judge Turnbull said these conditions played a role in the ex-teacher's offending.
In custody since his arrest in June 2022, Wormald will be eligible for parole in September 2029 with his full prison term expiring in February 2034.
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