Jesse Anthony Serrato, 29, is a teacher and physical education instructor at East Whittier School. He also is a part-time coach at La Serna High School.
School officials received information on Tuesday that Serrato may be involved with a female student and placed him on administrative leave pending an investigation, police said. The school then contacted police.
He was arrested at his home in Whittier and booked on suspicion of a lewd act with a child.
Anyone with additional information is urged to call the Whittier Police Department at (562) 567-9270.