ST. JOSEPH — A former teacher who threw a chair in his classroom, hitting and injuring a student, pleaded guilty Monday morning to a misdemeanor assault charge.

Thomas Barnes, 49, was fired from his job as an art teacher at Benton Harbor Charter School Academy earlier this month after he lost his cool in class and threw a chair, hitting 11-year-old Antownisha Johnson in the head. Her parents took her to the hospital after school and she was diagnosed with a mild concussion, her mother has said. The mother said the child was sent home on the bus at the regular close of school that day.