The authors offer a look at the debate about single-sex teaching, presenting insights from research about the consequences of gender division in schools. Drawing on classroom observations and interviews with teachers and students, the book illustrates the effect of single-sex classrooms on learners and on the versions of subject knowledge made available to them. In exploring the differences in teaching practices between boys’ and girls’ classrooms, in relation to subjects such as science, english, drama and technology, the authors show how single-sex teaching can create circumstances which limit rather than open up students’ access to subject knowledge. The authors offer tools for investigating the knowledge-gender dynamic, advocating that learning will expand if teachers work with gender to help students to cross boundaries into non-traditional gender territories within subject lessons.