Complex sentence: Since it's how teachers were taught as pupils, and how they were taught to teach, and given a focus on exam results as a way of measuring school performance, there may be impediments to a change in teaching style (Green and Hannon 2007).
Split into simpler sentences: Since it's how teachers were taught as pupils, and how they were taught to teach. Given a focus on exam results as a way of measuring school performance, there may be impediments to a change in teaching style (Green and Hannon 2007).