Holly Polson, 35, was an instructional aide at Shadow Hills Intermediate School. She's been in custody since her arrest in June.
Polson, who is married, is set to be sentenced next month and faces up to 14 years in prison.
The district attorney's office said the victim's mother called police and Polson was arrested last year. Authorities say she admitted having a sexual relationship with the student in a classroom and her car between May 29 and June 10, 2011.
City News Service contributed to this report.