Teacher

This is the act of showing or explaining something to someone so that they acquire new knowledge.

The scrum master is an expert in scrum and related agile practices. The scrum master spreads this knowledge throughout the organization, enabling people to engage in their work more effectively.

Mentor

This is a relationship in which a more experienced person helps to guide a less experienced person in the performance of their work. It includes the informal transmission of knowledge, social capital, as well as psychosocial support to enable broad on-going development. As the team is engaged in the daily use of scrum, the scrum master helps them use it more effectively. The goal of mentoring is to help the individuals become self-sufficient, and the team to become self-organizing.

Coach

In this activity the scrum master aims to improve the performance of an individual or team, in pursuit of an objective set by the individual or team. While it may include elements of teaching or mentoring, the focus is helping the individual or team to improve their own performance: in other words, helping them help themselves. One of the big differences between coaching and mentoring is who is setting the direction. When the scrum master is mentoring, it is the scrum master that is choosing the areas to focus on for improvement. In a coaching approach, the scrum master is helping the individual or team improve in an area of their choosing.