This classic book written in 1964 and updated in 1982 is a must for anyone teaching mathematics to pupils of any ages. Originally written as a series of memos to a colleague they were adapted and edited under four headings: Strategy; Fear and Failure; Real Learning and How Schools Fail. The revised edition keeps the original text and offers sidelined comments on how his views changed over time. Still highly relevant today the book has informed the recently produced Teaching for Mastery assessment materials produced by NCETM and OUP.