Over the past three decades the class size debate has been prominent in not only educational discourse but also the subject of public opinion and politics. While much has been debated about the instructional benefits and the financial implications of low teacher to student ratios, little has been written to document how teachers’ perceive the impact of class size on student learning. This large-scale study with over a thousand NSW public school teachers sought to determine the nature and dimension of teacher perceptions and practices about class size taken into account personal and environmental factors. The study also identified the strengths and weaknesses of teaching strategies used when teaching small classes.