The evaluation of observed lessons has been the subject of much debate in the field of teacher training. Teacher trainers have tried to define quality in relation to teaching and to find ways to measure it in a reliable way. Can we evaluate the quality of teaching by observable behaviour and measurable components, in which case, can the lesson be assessed analytically by the use of discrete criteria? Or, does a lesson constitute an entity, which cannot be broken into discrete components so that it has to be assessed impressionistically? We believe that in order to construct a more comprehensive view of the issue, it is pertinent to collaborate with our trainees and provide some space for their voices. Evidence from a small-scale practitioner-based research project reveals that trainees need explicit criteria for effective teaching in order to identify their strengths and weaknesses and use them as guidelines for improvement.