Fabian Sabbara, 15, was dressed in his school uniform when he was stopped by three police community support officers for taking photos of a station on his mobile phone.
He explained he was taking pictures, as well as pedestrian counts and a traffic survey, as part of a GCSE project.
But PCSO Barry Reeve told Fabian, from Cheam in South London, to sign forms under Section 44 of the Terrorism Act, which allows police to stop and search at random anyone they suspect of terrorism.
The pupil from Rutlish High School, Merton, was forced to comply or face arrest after he was stopped at nearby Wimbledon railway station.
After the incident, his mother Clare and father Felix contacted police to remove any record of the incident against their son's name - but were told it had to remain in place for six years. Mail Online