Questionnaires were completed by 5044 12-year-old pupils in Oxfordshire state schools and initially used to identify classes where the pupils were more positive and enthusiastic about their science lessons than the majority. The teachers of these classes were identified and the views of their pupils as to what happens in their science lessons obtained from the questionnaires. The factors that emerged as key components of good practice in science lessons were: teachers being good explainers; pupils engaged in practical work; the encouragement of thinking and discussion; and contextualisation of the science. The uniqueness of this study is in terms of its scale and the use of "pupil voice" both to identify "exemplary" teachers and to explore their practice. (Contains 2 tables.)