This work supports teacher trainees as they help students develop maths reasoning skills. It uses the Causal Connectivity Framework and enhances the knowledge and skills of trainees in sequencing teaching content with cumulative knowledge and understanding. It covers a variety of contexts from primary education up to GCSE level and includes practical examples of what is possible. The book offers maths teachers an alternative way of incorporating reasoning as a critical component of maths learning - a part of continuous professional development based on strong subject and curriculum content knowledge.