Juric also sent the undercover detective videos of young teenage girls, which the court heard were Category A – the most severe form of child sex abuse imagery.
There was no suggestion any of the children in the images were pupils at his secondary school or bore a likeness to any child at the school.
Juric was arrested on 17 January and found to be in possession of 380 illegal images including 31 Category A images.
Bishop Wilkinson Catholic Education Trust, which runs St Robert of Newminster School, said it “immediately suspended” Juric on learning that he was under police investigation and he no longer worked at the school or was employed by the trust.
The trust said it understood the charges did not relate to any school or individual in the whole trust and said its priority was to ensure all pupils and families felt “safe, supported and informed”.
Juric admitted three counts of making “pseudo” indecent photographs of children and one count of distributing indecent photographs of children.
He will be sentenced at Newcastle Crown Court on 22 December.