This session will focus on cultivating flexible thinking through the use of mental math as a foundation for all mathematical operations prior to the application of algorithms. Educators will explore the cognitive progression in mathematics—moving from concrete to representational to abstract thinking—and discuss strategies to support students in developing robust number sense through various flexible approaches and computation strategies. Participants will be encouraged to externalize their mental strategies and thought processes on vertical non-permanent surfaces, facilitating visibility and collaboration as they adapt shared strategies to meet the diverse needs of their students. By engaging in hands-on activities, educators will leave with practical tools to enhance their teaching and promote flexible mathematical thinking in their classrooms.