David Russell Bond (62), who is no longer teaching, was before the Dunedin District Court convicted of indecently assaulting the boy at Wanaka on or before May 18, 1975.
He was sentenced to four months' home detention and 100 hours' community work and is to pay $4000 emotional harm reparation.
The police summary said Bond, in his mid-20s at the time, and a colleague took five males on a tramping trip to the Mt Aspiring area in May 1975.
The group tramped to a hut which had bench bunks able to sleep up to a dozen people. One night Bond slept beside the boy.
They were in separate sleeping bags.
The boy was woken by Bond persistently pressing against his bottom and back.
The boy rolled away and went back to sleep but was again woken by Bond, who had put his hand inside the boy's sleeping bag.
Bond indecently assaulted the boy, who rolled away and tightened his sleeping bag drawstring so Bond could not reach inside.
Bond entered his guilty plea in March after a sentencing indication.
Counsel John Westgate said Bond expressed remorse for the offending.
The presentence report was positive in many ways.
In submissions for final name suppression, Mr Westgate said a letter from Bond's doctor stated should Bond's name be published he had ''serious concern for his increased suicide risk''.
Crown counsel Marie Grills said the material before the court did not meet the criteria for name suppression.
The victim was strongly of the view there should be publication.
It was part of his motivation in coming forward.
The victim did report what occurred at the time, but nothing came of it.
Unfortunately, that left him with a misguided sense of guilt he should have done more to bring it out into the open.
Judge Phillips said Bond, a teacher in a position of trust, had acted in a criminal way against a vulnerable boy ''in your care and protection on a school trip''.
The victim had had a good deal of his life destroyed.
Spoken to some time after, Bond said he could not remember the school trip and denied his action, the judge noted.
''I understand this boy went home upset,'' he told Bond.
''His mother recalls him coming home upset and angry. She went to someone from whom she could have expected assistance but got none,'' Judge Phillips said.
''I accept it happened in a different world. But you have to be held accountable today,'' he told Bond.
Declining final name suppression, the judge said there was strong public interest in the publication of names of people ''for this sort of offending''.
Non-publication could bring others under suspicion.
Special conditions of home detention are to undergo a psychological assessment with a departmental psychologist, and any follow-up; and to only engage in vocational training/employment, or any club or group, with the prior written approval of probation.
Bond is not to associate or otherwise have contact with anyone aged under 16 unless under the direct supervision of an adult approved in writing by probation; and he is not to have contact with the victim either directly or indirectly.
Post-detention conditions, including the special conditions, are to run for six months after the detention ends.
