As online spaces for mathematics content and lesson plans become more accessible, teachers are exploring these websites to make decisions about instructional materials for their courses. These resources then have an impact on what is enacted in the classroom and what opportunities students have to learn mathematics. One of the most popular online spaces teachers frequent is Teachers Pay Teachers (TpT). Using the Remillard and Heck's model on curriculum enactment, this study investigates secondary mathematics teachers' decision-making process and the heuristics they rely on when choosing mathematics content from online spaces, namely TpT due to its extensive use by educators. Findings suggest that these participants exhibit reliance on the availability, representativeness, anchoring and adjustment, and groupthink heuristics.