Catch Up Numeracy is a one-to-one intervention for primary school children who are struggling with numeracy. It consists of two 15 minute lessons per week for up to 30 weeks, usually delivered by teaching assistants (TAs). To prepare them to deliver the intervention, TAs are supplied with detailed lesson plans and receive four half-day training sessions. The intervention breaks numeracy down into ten components, assesses children’s ability on each, and targets subsequent instruction so that the tutor always addresses the exact area of weakness. The evaluation was funded by the Education Endowment Foundation.