This book documents and explores the ideas of school students (aged 10-16) about a range of natural phenomena such as light, heat, force and motion, the structure of matter and electricity. It also examines how students' conceptions change and develop with teaching. The editors have brought together science educators who come from different parts of the work but whose work is focused on the same determination to bring insight into the conceptual world of children in science classrooms - insight which will be helpful in making science teaching and learning more rewarding for teachers and children alike.