Two days earlier he had received his first-aid certificate after completing a three-day course.
Josh held Maihi Douglas until he stopped shaking.
He then put him on the ground in the recovery position and asked another pupil to ring an ambulance.
Yesterday, he told the Otago Daily Times it had been a "scary" experience, but he was pleased his first-aid training had paid off.
Constable Stef Witehira, of Palmerston, said Josh had done "very well".
The accident was attended by a nurse from the Palmerston Health centre, the Palmerston Volunteer Fire Brigade and the Otago Regional Rescue Helicopter.
East Otago High School arranged for all their senior pupils to complete the first-aid course, deputy principal Jan Malloch said.
Maihi Douglas was admitted to Dunedin Hospital for assessment.
