Teaching that attends to and builds on students' resources and treats students as capable mathematical sense makers has been referred to as responsive teaching. A body of research reports teachers' tendency to overlook students' mathematical thinking when their answer is correct and to correct it procedurally when students make a mistake. This practice prevents teachers from gaining insights about students' underlying mathematical understanding regardless of the correctness of the answer and noticing the potential for conceptual understanding. Teachers need support to use students' mathematical thinking as a source for mathematically responsive pedagogical actions. In many studies, pre-service teachers' responsive pedagogical practice is studied in the later stages of the teacher education program in relation to field placements, which may cause a separation between learning to teach and doing the work of teaching. In this study, I investigate the potential in the mathematics content course to support PSTs in developing their ability to respond to students' mathematical thinking to deepen their mathematical understanding. To that end, I designed a semester-long intervention in the content course which is typically the first course PSTs take in relation to learning to teach mathematics. I used Jacobs et al.'s (2010) framework of professional noticing of children's mathematical thinking to design the course materials. The key finding of this research uncovered the potential in content courses, where PSTs are beginning to develop their mathematical knowledge for teaching, to address the skills required to notice children's mathematical thinking. In addition, the results confirmed previous research findings by showing that a high level of attending to student ideas is necessary to develop a response that leverages students' mathematical thinking; solely developing this skill is insufficient to craft sophisticated responses. Pre-service teachers in this study began to probe each other's thinking by asking for evidence and to challenge each other about how the proposed response aligned with the instructional purpose. The findings indicate that PSTs could broaden their vision of better possibilities to leverage children's mathematical understanding. Implications for future research call for aligning noticing with asset-based mathematical teaching. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]