This series is for maths teachers who want to develop their maths teaching skills. This book is for teachers and educators who want to develop their maths teaching skills where English is the language of instruction. It has been written by the international group of educators based at AIMSSEC, The African Institute for Mathematical Sciences Schools Enrichment Centre. The book provides practical classroom activities underpinned by sound pedagogy and recent research findings. The activities are designed for teachers working alone or in 'self-help' teachers' workshops. They are designed to develop mathematical thinking and offer immediate practical tools to help deliver this approach.