A 15-year-old boy who claimed he had sex with a teacher said he was "scared" when rumours of their alleged relationship spread around his school.
Kandice Barber, 35, of Wendover, Buckinghamshire, denies three charges of sexual activity with a child.
The jury heard she is being tried for a second time after a first trial was unable to reach verdicts.
The prosecution alleges she messaged the boy repeatedly and drove him to a field where they had sex.
Prosecutor Richard Milne told jurors at Amersham Law Courts that at Barber's first trial last year, she was convicted of sending topless pictures of herself to the boy.
The court heard that Barber had approached the boy - who cannot be named for legal reasons - at a sports presentation in September 2018, and took his phone before adding herself to his Snapchat, which the boy thought was "a bit weird".
Mr Milne said messages had initially been normal, but had "become sexual" about a week later.
Prosecutors said Barber picked the schoolboy up in her car in October 2018 before driving to a "private" area where they had sex in a field.
'Worried and scared'
The court heard the boy had initially lied to his head teacher in January last year about the relationship and that Barber had allegedly told him she could be pregnant with his child.
"She said he should deny everything and should delete all the messages," said Mr Milne, adding that the boy had felt "worried and scared".
In a video interview shown to jurors, the boy said it had been "awkward" seeing the teaching assistant in school afterwards.
"I began to panic and didn't know what to do in that situation... I didn't know what was going on," he said.
He alleged that she called him in tears after learning she had had a miscarriage.
Mr Milne said that Barber told the boy she would "bring him down with her" if he "snitched", by making a false allegation of rape.
The trial continues.