Set within the context of the longitudinal Cornerstone Maths project in England. we adapt Thomas and Hong's theoretical framework (mathematical) ‘pedagogic technology knowledge' (MPTK, Thomas & Hong, 2013) to explore teachers' espoused knowledge to teach with dynamic mathematical technology in lower secondary mathematics. We conclude a set of eight ‘quality features' of such plans, and highlight how each of these features can provide a dynamic insight into teachers' MPTK development over time.