Authorities say the incident occurred Tuesday at a junior high in Kankakee, which is about 60 miles south of Chicago.
According to a police statement, the officer used the Taser on three male students who volunteered to be part of the classroom demonstration.
Police say the officer was not authorized by the school, the district or the police department to do a Taser demonstration.
A parent later took one student to a hospital, where he was examined and released.
