Understanding how students use math strategies is important to help us build tools and techniques that improve cognitive flexibility in students, i.e., to select strategies that are appropriate and efficient for a problem. In this work, we focus on instructional content within MATHia, where students choose between strategies that were previously taught to them independently. Some problems favor one strategy over the other, giving us the opportunity to understand how/if students learn to pay attention to problem characteristics that suggest one strategy over the other. Using data from over 600 schools, we show that students find it hard to adapt their strategies to suit a problem. Further, we learn a BERT model to learn embeddings for strategies, develop a prediction task to distinguish between successful and unsuccessful strategies, and analyze its results to reveal deeper insights into student strategies.