Working Memory is the ability to remember information and work on it at the same time. You use your Working Memory every time you do arithmetic. The Working Memory Plus Arithmetic (WM+A) is a programme especially designed to promote the development of children’s working memory in the context of mathematical tasks. It contains two parts: a working memory intervention and an arithmetic intervention. Both parts were found to be effective in a study with 127 schools funded by the Education Endowment Foundation. The results of this study are summarised in a research brief, which describes the programme and its impact on children’s working memory, arithmetic and attention in the classroom.