A teacher accused of sexually touching girls in his class was known as "Mr Perv" at his school in East Yorkshire, according to one of his alleged victims.
Science teacher Christopher Hird, 47, is on trial accused of sexual misconduct with three girls at a secondary school. One of them was 11 years old at the time of the alleged incident.
Prosecutor Simon Waley told a jury at Hull Crown Court how each of the allegations involved "brief and subtle" touching but said Hird "was someone they should, of course, have been able entirely to trust".
Mr Waley said: "Although they were brief and subtle, they are clearly touchings that have upset and stayed with the girls concerned."
The jury of six men and six women was told the first girl who came forward alleged Hird had touched her twice during lessons, in separate incidents in 2011 and 2012. She was 15 years old when she said it first happened.
In the first incident, she said, the teacher wiped ink from her face, stroking her in a way she found "quite disturbing". She claimed he pressed himself up against her in a unnecessary way.
In the second, she said, Hird came up behind her in the classroom when she asked a question.
She said he pressed himself against her, put his hand on her side and slid it up and down. The prosecutor said Hird also placed his hand on the chair between the girl's legs.
When the incident was reported, the school told police about another allegation that had been made about Hird in 2009.
Mr Waley said this girl, who was 16 years old at the time, told police Hird was known among pupils for blatantly staring at girls' chests and was known at school as "Mr Perv".
She accused Hird of brushing his hand against the side of her breast in class.
Mr Waley said: "She was so upset about what happened, she decided to drop chemistry as a subject."
The court was told that a third girl came forward after Hird was charged with offences and a story about the case appeared in a newspaper.
This girl said she was 11 years old at the time and in her first week at the school, Mr Waley told the jury.
According to the prosecutor, she claimed the teacher stood behind her and touched her inappropriately as he removed a piece of paper she had been sitting on.
He said Hird also ran his hand down her hair braid and stroked her face saying:"Did you think it was a spider?"
Mr Waley said Hird denied any misconduct during his interviews with police. In relation to the girl who came forward after reading the newspaper report, the prosecutor said Hird remarked: "When you think I have taught thousands and thousands of students, then it's open season."
He said the defendant suggested the girl may be motivated by compensation.
The court heard that Hird has been a teacher for 24 years. Dressed in a suit, he sat in the dock listening to the prosecution opening statement. He has pleaded not guilty to four charges.
He denies indecently assaulting an 11-year-old girl between August 31, 2000 and October 1, 2000. He denies sexually assaulting a girl between February 1, 2009 and February 8, 2009.
He denies sexual activity with a child under 16 between January 31, 2011 and April 1, 2011. And he denies sexual assault of a girl between April 15 and April 21, 2012.