A head teacher asked a police officer to give pupils a ticking off for pulling faces in their school photograph.
Children were left 'in tears' after the officer reprimanded the 10-year-olds.
The extraordinary claims were made at a tribunal in Wales which heard that head Ann Hughes ran village primary school Ysgol Goronwy Owen, in Anglesey, in a 'climate of fear'.
It is alleged she swore at pupils and showed favouritism to those whose first language was Welsh.
When a group of classmates tried to sabotage the end of year picture because their usual teachers were on strike, she responded 'excessively' by asking school liaison officer PC Brian Jones to reprimand them.
Mrs Hughes was later suspended and then sacked from the school in Benllech.
There had been a catalogue of complaints from teachers and parents, which included calling children names, excessively shouting and punishing them in public.
Mrs Hughes, 64, who previously had a 40-year unblemished teaching record, appeared before the Professional Conduct Committee of the General Teaching Council for Wales, sitting in Ewloe, near Queensferry, north Wales.
The mother of one pupil said her son had come home from school 'absolutely distraught'.
She said: "He was crying his eyes out, saying he was never going to school again.
"My dad was a police officer, he has respect for them. He was absolutely terrified."
PC Jones admitted some of the children, who had begun a petition and circulated a note to encourage others to sabotage the photo, broke down after he told them he was disappointed with their behaviour.
He said: "I spoke to them as a class, I didn't speak to any individual children.
"I told them how some of them had made a member of staff cry and how a few of them had ruined the photo for the whole class.
"I told them that if they had an issue they should have talked about it and should not have been seeking to sabotage the photo or manipulating others.
"One or two did break down and start crying, I remember a large number of children turning to look at those responsible. In my view they were crying because of the guilt at what they had done."
Presenting officer Martin Jones suggested the reason the children were upset was because they thought they were in trouble with the police.
PC Jones said he would be 'inordinately surprised' if they believed it was a criminal matter, although he admitted he could not be certain.
Mrs Hughes, from Llanfairpwllgwyngyll, faces further allegations including that she used the word 'c**p' when speaking to pupils, repeatedly called one child 'twp' - the Welsh word for 'stupid' - and shouted excessively in the classroom.
She is also accused of failing to investigate and address bullying of two pupils, highlighting parents' complaints during school assembly thereby potentially identifying pupils, and engaging in unnecessary open criticism of children's mistakes.
Further claims include openly criticising a pupil's error in the spelling of his middle name and tearing up his SATS examination paper in front of him, and being insensitive by commenting on the length of a pupil's absence to his brother following the death of their father.
The hearing continues.