Answer: The conflicting demands of the two positions.
Explanation: Although similar in work activity, which is to pass knowledge across to a learner, teaching and coaching have some key differences.
The teacher is not very obliged to ensuring the success of each student, but is satisfied if a large percent succeeds out of the total number of students.
While a coach is more patient in his approach, nurturing his student step by step, the coach is very interested in the success of each student and is not satisfied if even a single student fails.
Therefore there is a role clash if the responsibilities of a teacher and a coach is closely observed.