In this paper, we describe how we came to use timed fluency activities, along with personal learner reflections on those activities, in our after-school maths club as a complementary research and development tool for assessing the changing levels of learners' mathematical proficiency over time. We use data from one case-study after-school maths club. Not only did the activities provide us as researchers, and mentors, with a quick way of tracking, evaluating, encouraging and valuing learner progress, but also with a mechanism for the learners to practice the fluency they were developing through other activities of the club. More importantly, the use of learner reflections assisted learner buy-in and reduced the stress related to such timed assessments. This alleviated, to some extent, our ethical unease with the use of such instruments. We have subsequently extended this research and development tool in all clubs that we run and continue to research their affect and effect in order to gain deeper understanding of the research and development opportunities enabled by such activities. (Contains 2 tables and 2 figures.)