Methods courses in teacher education programs often stress the importance of planning and preparation. However, there is no real substitute for experience and ongoing professional development; learning for a mathematics teacher is a continuous endeavor. While university coursework is helpful, the preparation for planning discussed in this coursework is often in relation to idealized situations and scenarios. It is quite rare when what is planned for and what actually happens in the mathematics classroom align. The authors suggest that new teachers begin, as early as possible, to develop the "Plan B" ability. By this, they mean the capacity to reflect on and adapt to unexpected situations in the classroom by developing and implanting new, real-time action plans to address emergent goals. Flexibility adapting is a skill in itself and is a function of several factors, including: (1) a teacher's confidence in, and depth of understanding for, their content knowledge, which allows them to make well-reasoned pedagogical decisions in response to unanticipated classroom occurrences; (2) a teacher's ability to build a community of learners who trust the adjustments a teacher needs to make in response to unexpected twists and turns in the classroom; (3) a teacher's ability to assess, individually and collectively, where students are in the learning process, from moment to moment; and (4) a teacher's willingness to reflect, record, and revise their lesson plans and goals. In this article, the authors make suggestions in each of these areas as a way to support and empower new teachers.