Sophie Elms, now 18, committed the "devastating" sexual offences against two young children aged just two and three years old, Swindon Crown Court heard.
The list of sixteen sexual offences she previously admitted included penetration, sexual assault, and taking and distributing indecent photographs of the children. She was sentenced to seven years and ten months behind bars.
The court heard that, at the age of 16, Elms had just started attending Swindon College, and was undertaking a placement in childcare.
Prosecutor Hannah Squire said Elms was left in charge of the children in 2016 and 2017.
But in early 2017, Elms began having online contact with sex offender Geering - who was later sentenced in November 2018 to 15 years in jail for child sex offences.
She carried out the attacks after Mr Geering incited her to abuse them and send him lewd pictures.
Miss Squire added: "Miss Elms started out with innocuous photos of the two children - that is, fully clothed - sent to David Geering.
"But this soon moved on to pictures of the children naked, and images of Miss Elms touching the children - which, to an extent, were requested by David Geering."
Between December 2016 and March 2018, Elms went on to commit four counts of sexual assault against the youngsters - two against each child.
She also committed four counts of taking indecent photographs of children - two category A photos, four category B photos, and one Category C photo.
She also committed six counts of distributing indecent photographs of children - four category A, four category B, and four category C.
In a police interview in April 2018, following her arrest on March 10, Elms told police that Geering must have obtained her details from somewhere online.
She said that she liked talking to him, as she had "low confidence" and he "made her feel good".
Defending, Chris Smyth said that his client had been groomed from the age of 13 by four separate males - at least two of whom have been prosecuted.
Elms sobbed in the dock as the father of the two young girls read out a distressing victim impact statement.
He said: "The damage Sophie Elms has caused to our family is unimaginable.
"Our two beautiful daughters looked up to you. We asked you if you wanted to care for them overnight, to help with your studies.
"Not for one moment would we have imaged that this decision would change our lives forever.
"We honestly do not know full extent of damage you have left on our two beautiful babies. What you did could have serious long-term effects on them in their later lives.
"We have such a complete lack of trust to anyone with our children now.
"Even leaving them at pre-school is a challenge to us, as this was the profession in which you were training.
"Our youngest daughter is so distraught at bedtime that we have to stay with her for several hours.
"We have made the decision that we cannot stay in Swindon for fear of bumping into you - and that it will be better for us to move [abroad].
"This whole horrific event has damaged us beyond words.''
Judge Jason Taylor said: "The parents of these children were comforted by the fact that you were doing a childcare course. In my judgement, this was a breach of trust.
"They never suspected you would breach the tremendous trust they placed in you - but you did.
"In a deliberate and calculated manner, you targeted these young children. With a sinister and hidden agenda, you deceived the parents of these children to gain access to the children.
"Your behaviour had elements of planning. It was sustained, it was offensive. You knew it was wrong.""You have no control of what Mr Geering did with those images. No-one does."
''You are a good manipulator. You wanted to appease the man towards whom you felt affection, and you wanted his attention."You prioritised these things over the welfare of young, vulnerable children in your care."Their families are broken people, and you're the one that broke them. They will never recover."Judge Taylor acknowledged that Elms was a "troubled girl", and that she was "targeted and exploited" by Geering - who was sentenced for 15 years at Shrewsbury Crown Court in November.Following today's sentencing, Det Insp Simon Childe said: "Understandably, this case has shocked the local community as well as those further afield.''Elms is just 18-years-old making her one of the youngest women in the country to be convicted of these types of offences, and at the time of committing these atrocious crimes, she was studying child care with a long term aim of working with very young children in the future.''I am extremely grateful to my team of dedicated officers who have been able to intercept and prevent her from working with children ever again."I would like to firstly praise the families of the very young victims in this case who have shown a great deal of strength throughout this court process.''They have been provided with specialist support since the investigation began and we will continue to ensure they and their children feel fully supported."Secondly, I would like to praise the investigation team in this case who have worked tirelessly and very closely alongside partner agencies in pulling together evidence to put before the courts and ensure Elms could be brought to justice for her disgraceful actions."Our officers will leave no stone unturned in investigating crimes of this nature regardless of how much time has passed since the offences were committed.''We understand the huge impact these offences can have on a young victim and their families. I hope that in this case, the families of the young victims can take some closure from the sentencing and feel supported in moving forward."As well as her jail term, Elms was made subject to a sexual harm prevention order and an indefinite restraining order.