Mr. Perez and Mrs. Peterson co-teach a ninth-grade algebra class. Perez and Peterson's class includes four students with individualized education programs (IEPs). In response to legislation, such as the No Child Left Behind (NCLB) Act (2001) and the Individuals with Disabilities Education Improvement Act (2006), an increasing number of students with disabilities are taking mathematics classes, including algebra, in inclusive settings. This situation brings up key questions: Which instructional methods can teachers such as Perez and Peterson use to determine if instruction is working for all students in their mixed-ability classroom? Which daily instructional methods can teachers implement to ensure that all students are making progress? One method for monitoring student learning is formative assessment. As part of a project funded by a state department of education grant, mathematics teachers received professional development (PD) in the principles of formative assessment to enhance the learning of all students in their classroom, including those with exceptional learning needs. This article shares the formative assessment methods spotlighted in this project, along with how formative assessment was implemented in two algebra classrooms. Through the formative assessment project, teachers received PD on formative assessment provided by university faculty with expertise in mathematics education and instructional methods for students with exceptional learning needs. The teachers were supported in implementing formative assessment methods by coaches who observed instruction and provided feedback and suggestions. Specifically, the teachers formed professional learning communities and agreed on the use of specific questions to guide implementation of formative assessment repeatedly in their mathematic classrooms. Throughout the project, teachers received PD on formative assessment methods, including breaking problems into steps for error analysis; using data collection charts to identify student response patterns; providing multiple probes to assess student understanding; and embedding one key question into a formative assessment for analysis. This article provides classroom examples using these methods, along with how each teacher adjusted instruction based on the resulting student formative assessment data.