As teachers prepare for mathematics lessons they make instructional plans based on their knowledge and available resources. A teacher's capacity to mobilise resources to design lessons is known as his or her pedagogical design capacity. This study analyses shifts in the pedagogical design capacity of four teachers as they transition from lesson planning to lesson implementation in the classroom. Results indicate that teachers' pedagogical design capacities are reflected differently from the time of lesson planning to the time of instructional delivery, with a shift toward less curricular reliance during implementation. Findings indicate that teachers would benefit from support to know how to make changes, while teaching in ways that will best develop students' mathematical thinking. Additional work focusing on the role of context as related to pedagogical design capacity, would provide further insight for understanding teachers' abilities to use resources for mathematics instruction.