The court heard that the victims suffered from depression
A 81-year-old former school teacher has admitted sexually abusing three pupils almost 30 years ago.
The High Court in Glasgow heard that John Pringle, a languages and guidance teacher at Bishopbriggs Academy, abused the 13-year-old boys on school trips.
The court heard Pringle promoted outward bound trips, which the victims now believe were used to lure them to areas where he would be unsupervised.
Judge Lord Woolman deferred sentence for background reports.
Pringle admitted using lewd, indecent and libidinous practices towards a 13-year-old boy on one occasion in 1979.
He also pleaded guilty to lewd, indecent and libidinous practices towards two 13-year-old boys on various occasions between 1980 and 1981.
Derek Ogg QC, prosecuting, said: "All three were pupils at Bishopbriggs Academy.
"Pringle promoted the idea amongst the boys of attending 'outward bound' type activity such as hill-walking and canoeing.
"These events, unsupervised by any other adult and uninspected by the school authorities, continued over a number of years."
Mr Ogg said the first incident happened when Pringle shared a double bed with a boy.
The other boys estimate they were abused on 10 separate occasions.
Mr Ogg added: "Neither boy at the time saw anything wrong in this conduct.
"It was only after they grew up and became more socially aware they realised to their distress that this conduct had grossly breached the trust inherent in a teacher-pupil relationship.
"They now feel the outward bound events were a lure to entice them and then retain them in the thrall of Pringle."
Both suffered from depression, anxiety and feelings of low self-esteem, he added.
He said: "While the two complainers each resent and feel betrayed by the abuse they at the time liked and admired Pringle himself."
Frances Connor, defending, said: "I am instructed, for what it is worth, to offer to these people his unreserved apology and acknowledgement that what he did was wrong and to express his remorse at the consequences to these people as the result of his actions."