Grant Blair, 41, of Cupertino, was arrested without incident at a park in San Jose on suspicion of illegally meeting a minor to engage in lewd or lascivious behavior, police said.
Grant has been a teacher of fourth and fifth grade students at the Old Orchard School in Campbell for about a year, police said.
The department's Internet Crimes Against Children task force contacted Blair online and an officer posed as a 13-year-old minor who agreed to meet Blair at the park.
When Blair showed up at the designated time and place, police arrested him at 4:45 p.m.
The Campbell Police Department interviewed about 35 students at the Old Orchard School to find out if there were any unreported acts of lewd or other inappropriate conduct, San Jose police said.
The investigation, with the cooperation of school administrators, did not discover any prior incidents, police said.
San Jose police are investigating Blair's previous places of employment, police said.