A teacher who called himself the "Salford Stallion" had sex with three of his female pupils, a court heard.
Christopher Drake, 29, of Monton, worked as a PE teacher at a school in Greater Manchester, and was later promoted to assistant head teacher.
He has previously admitted to 18 counts of sexual activity with a child.
Manchester Minshull Street Crown Court heard how he had been sleeping with two girls since they were aged 14 and had also slept with a 16-year-old student.
His affairs were uncovered on Valentine's Day last year, when two of his victims discovered he was seeing them at the same time.
The "hysterical scenes" which followed in the early hours of the morning led to police being called out and Drake was arrested.
Justin Hayhoe, prosecuting, said the 16-year-old recalled Drake used to give her lifts home and went on to flatter her with remarks about her looks.
He then managed to get hold of her mobile phone number without asking her and texted her smiley faces.
Mr Hayhoe said she then realised who he was when one of the texts was addressed from "Salford stallion", a nickname he liked to use and one that his pupils knew him by.
The other two girls began their relationships with Drake in early 2008 and in September 2008.
Both were unaware of each other until 14 February 2010.
'Revelled in popularity'
In mitigation, Adam Watkins, defending, said Drake did not coerce, bully, belittle or manipulate the girls.
He said: "He has more recently had a growing awareness of how wrong, inappropriate and potentially abusive and damaging these relationships were."
Mr Watkins said Drake was seen as a hard-working teacher who was promoted and revelled in his popularity but he had failed to establish appropriate boundaries.
Judge Timothy Mort will sentence Drake on Tuesday after hearing victim impact statements from the girls involved.