Mr Colligan left school 12 years ago but is now following up his triumph by taking three Advanced Highers in biology, chemistry and physics. After that he wants to take a year out in Canada before heading to university.
He said: "I've supported the pupil since S1, and when I was sitting in on his Standard grades I decided to study alongside him after the school's SQA (Scottish Qualifications Authority) co-ordinator said that would not be a problem.
"I always felt I was capable of doing better than I did at school (Wester Hailes Education Centre). I didn't really apply myself at school where I got only threes and fives at S grade."
Mr Colligan added: "It was like I was resitting them and then the Highers seemed possible. After the Advanced Highers I'd like to go on to university, though I'm not sure as yet what I would like to study.
"It's been great to learn as you work and to get back into studying."