Veronica Ramirez, 25, was arrested Friday and booked at the West Valley Detention Center in Rancho Cucamonga, according to the San Bernardino County Sheriff's Department. She was being held on $2 million bail.
At the time of the alleged crimes, Ramirez was a teacher's aide at a private school for special-needs children.
According to a criminal complaint filed against the defendant, a sexual relationship between her and the male victim began in September and continued until December.
At an arraignment on Friday, Ramirez pleaded not guilty to four counts of lewd or lascivious acts with a child and three counts of oral copulation with a minor under 14, all felonies.