This document summarizes a study on designing and delivering a continuing professional development (CPD) course on mathematics for A-level Biology. It involved biology teachers in designing the course content on exponentials/logarithms and statistics. The day was delivered to 20-30 teachers. Data was collected on the impact on teachers' math confidence and teaching practice. Preliminary findings showed the design process improved math teaching confidence and the day further increased statistics confidence while providing pedagogical support ideas. Challenges included time away from school and differing research/practice cultures.