Abstract
This study looked at how student teachers created and altered mathematical assignments using their pedagogical and subject-specific knowledge of mathematics. It also looked at the connection between instructor expertise and a task's cognitive requirements. The framework of Hill, Ball, and Schilling outlines many domains of knowledge in mathematics for instruction. The Stein, Smith, Henningsen, and Silver framework also characterizes the cognitive demands of mathematical tasks in research. Findings show that when student teachers lack the expertise in other areas, particularly subject matter expertise, required to accomplish specific educational tasks, they focus on knowledge of shared content. was shown. When the student's teacher changed the task, the cognitive demands of that task often decreased. These declines are often related to a lack of subject matter expertise.