Graham Brennand, 70, of Calder Avenue, Freckleton, is accused of a string of sexual assaults, physical assaults and one of cruelty against former pupils - some dating back more than 40 years.
He is accused of 29 charges involving 17 girls and two boys at a time when he worked as a teacher and deputy head at a primary school in East Lancashire. They span a period between 1974 and 1989.
Prosecuting at Preston Crown Court, Bob Golinski said: "In your final year you were in his class.
"You obviously had dealings with him in the classroom. What is your recollection of any physical contact?"
She replied: " He used to on a daily basis check whether you were wearing a bra or not by running his finger from the top to the bottom.
"I wore a crop top rather than a bra. He used to run his finger along the hem of the crop top."
Asked when it would happen she answered: "Whenever he used to come over to the table to stand behind to check the work you were doing, whatever the subject was."
Mr Golinski asked: "If he's come to the desk where you're working there's a possibility of some sort of accidental contact - was that what this was?"
She said: " No, because he checked for a bra or crop top or whatever you were wearing, and ran his finger underneath the elastic."
She told jurors he would touch her underwear whilst holding a 'splint' at the top of her leg during a first aid class, when she was made to act as the 'patient'.
Earlier in the hearing, a man gave evidence alleging Brennand had slapped him across his head and legs, and had also locked him in a cupboard.