The use of SAFMEDS cards, which stands for ‘Say All Fast Minute Every Day Shuffled’ has been widely reported in the literature as an effective fluency-building tool. Most studies have focused on students with a learning disability or those classed as at risk of failing academically. In addition, most of the research has implemented SAFMEDS one-to-one or in small groups. We investigated the use of SAFMEDS in a high school setting, targeting basic maths skills across the whole class. Forty-eight students aged 11 to 12 years participated in the study over a four-week period. Our results showed that using SAFMEDS to compliment students’ maths lessons can further increase basic maths skills when compared to standard maths classes alone. We also found that the gains were maintained at a one month follow-up. An application quiz showed that students could also transfer the information they had learned to real-world maths problems.