I am writing objectives for one of my developers at the moment and we want him to take on some of the mentoring of a more-junior developer, partly as a means of increasing his seniority and partly because mentoring benefits both parties, so he'll learn something from the experience too.
The team in question is relatively small and they are going to be meeting regularly to peer-mentor and walk through project show-and-tells, for example, so how he might achieve this objective isn't too much of an issue. The problem I'm having, though, is that I'm struggling to work out how to make such an objective be measurable — in the sense of SMART objectives.
What sort of criteria would people here use in order to measure the success or failure of an objective around "having a greater input in the mentoring of junior members of staff"?