The Pierce County prosecutor has filed charges against a 24-year-old Tacoma, Wash., high school math teacher accused of engaging in sexual conversations and activity with three teens, including two current students and a former student.

Meredith Powell pleaded not guilty Friday to two counts of third-degree child rape and communicating with a minor for immoral purposes. She was released on personal recognizance.

Prosecutor Mark Lindquist alleges that on Jan. 17, one victim went to Powell's Lincoln High School classroom instead of attending an assembly and the two kissed and "engaged in sexual activity."

A few days later, Powell is accused of performing oral sex on another victim.

Prosecutors allege Powell exchanged explicit text messages with the victims and sent one a photo of her naked in a bathtub.

The News Tribune reports the teens are 16 and 17 years old.

Powell's lawyer did not immediately return a phone call for comment.