A gym teacher at Ronald H. Brown Middle School pleaded guilty yesterday to having sex at the Northeast Washington school with two 14-year-old students, one of them a learning disabled girl who bore his child.

Calvin S. Kinney, 47, is the second D.C. middle school teacher this year to admit a felonious sexual affair with a young student. The maximum penalty for his crime is life in prison. Superintendent Arlene Ackerman was away on vacation and could not be reached yesterday for comment.

D.C. Superior Court Judge Patricia A. Wynn was told that Kinney called the disabled girl into his office in late 1997 and asked her to lie on the floor of the bathroom attached to his office. He had sex with her and later gave the girl $20, prosecutors said.

The girl did not tell school authorities. Her story came to light a few months later when the second 14-year-old girl, who was doing a high school community service project with Kinney, told her grandmother that she was sexually involved with an older, married man.

D.C. police investigated. The man turned out to be Kinney. The girl said she had three sexual encounters with Kinney in 1998 at the school, from which she had graduated the year before.

In court yesterday, Kinney pleaded guilty to one count of first-degree child sexual abuse and one count of attempted child sexual abuse. DNA testing showed that the Forestville man fathered the disabled girl's child, said Assistant U.S. Attorney Ann M. Carroll.

Kinney's actions were "inexcusable," and the teacher should be fired immediately, said Barbara Bullock, president of the Washington Teachers' Union. D.C. school officials said Kinney was placed on administrative leave April 1, 1998, and will be fired as soon as confirmation of his conviction has been received.

"It should not be tolerated," said Bullock. "These students have been put in our care. We're supposed to protect them, not violate their rights."

Kinney has been a D.C. school employee since 1991, a school spokeswoman said. He worked at Randle Highlands Elementary School before going to Brown in 1995, according to Helena Jones, who was principal of Brown (then called Roper Middle School) until 1996. Jones's husband is principal of Randle Highlands, and Jones said Kinney had no problems there. Kinney also had been an assistant football coach at Eastern High School.

"Lord Jesus--this takes me by surprise," Jones said when told of Kinney's crime. "That is absolutely shocking and disappointing."

Jones, who has since left the school system, said that Kinney's office was in an area in front of the girls' locker area. He could not see their lockers from his office, she said, but no doors separated his office from the locker room.

Jones said that when she was principal, she always assigned an aide to be in the girls' locker room while the girls were changing clothes to protect against any male intruder. She said she was comfortable with the setup, and noted that any male teacher could enter any locker room or anywhere else in the building, regardless of whether there were doors.

In May, Shaw Junior High School band teacher Lorenzo McCrea, 39, was sentenced to five years in prison for having a months-long sexual relationship with a 15-year-old Shaw student. McCrea at first denied the affair to school authorities and the girl's father, but later pleaded guilty to enticing a minor child. Ackerman ordered an inquiry into McCrea's case after an assistant principal at Shaw wrote a laudatory letter to Judge Henry F. Greene on McCrea's behalf.