They were forced to strip naked in the rain and then were then slapped, punched, and kicked repeatedly.
The boy was spotted "negotiating" with his assailants before a disagreement led to the incident.
The teacher also took the opportunity to educate his students on encounters with wildlife.
It is unclear who the attackers were.
A warden found the boy unconscious in the early hours of 22 March.
The tutor even reportedly hit her face with a "metal rod".
The two 19-year-old robbers were reportedly arrested by police within 24 hours.
The suspects also allegedly confined his grandmother to a closet for three months.
The victim reportedly failed to pay her "friend" commission for introducing clients to her.
The teenager was stripped of his clothes in public and sent to the police station.