The trial of a former teacher accused of having sex with several students has launched with graphic testimony, including a mobile phone video that allegedly captured one of the sexual incidents.

Brittni Colleps, is facing a Texas court on five felony counts of having inappropriate relationships between a student and a teacher, US media has reported.

One student, who was 18 at the time of the alleged sexual misconduct, testified in court under the pseudonym "Aaron" spoke about several incidents he says took place at the teacher's home in Arlington where Colleps lives with her military personnel husband and their three young children.

When asked to describe what occurred in the house that night by the prosecution the victim stated, "We all started performing oral sex and having sexual intercourse with her."

"Aaron" also detailed explicit text messages he allegedly exchanged with the teacher.

The prosecution showed graphic mobile phone video to the judge and jury, excluding the media and people in the public gallery, allegedly showing a sexual incident that occurred in Colleps' home sometime around April 2011.

Colleps' defence attorney declined to give an opening statement and did not respond to the accusations.

All five students involved in the alleged group sex act will testify in court after the trial is set to resume on Thursday.

While the students were all legally allowed to have sex, in Texas it is against the law for a teacher to have a sexual relationship with a student.