In a release, the department's juvenile aid bureau said the male student was taking a test in a French class at about 9:40 a.m. when the teacher saw him cheating. The student was asked to change seats but refused. The teacher called security, and the student was escorted from the classroom, police said.
The student returned and when asked to leave again, he refused, police said. When the teacher went to call for security he was attacked by the student. The release said the student "proceeded to punch, kick and stomp on the victim."
The teacher received contusions to his head and upper torso, police said, and lacerations to the inside of his mouth. He was taken to Nassau University Medical Center in East Meadow, police said, treated and released.
In an e-mail release, Uniondale School District Superintendent William Lloyd said "proper protocol, including calling the authorities to escort the student off school grounds" was followed.
Lloyd was not available for questions and his office referred all questions to the district's public relations firm. A spokesman said he was not sure if the student had been suspended.
The student was taken into custody and charged with second-degree assault. Police have not identified him because he is a minor.
The student will appear in Family Court in Westbury on Wednesday, police said.