do you do first? I asked Anna as we looked at another long division problem. Divide 5 by 3, she replied. Correct! See, you know how to do this. Once again, I went through the steps of long division with Anna. I watched her usually smiling face change at the start of every math lesson and turn to a frown as she became lost again in the steps of long division. It seemed that no matter how many times I worked with her independently or how I addressed the problem, she still struggled. She began to give up, and so did I. She wasn't the only struggling student in my class. I watched students become discouraged and frustrated during math lessons, and their misunderstanding of math was evident when they repeatedly failed math assessments, yet I felt compelled to move through the curriculum swiftly for the sake of advancing students and in order to teach all math content before the year's end. How could I help my struggling math learners? Anna and other low-performing students weren't the only problem within my math class. A handful of students were ready to go far beyond where I kept them in our math curriculum. Although I challenged advanced students with alternative assignments, I unfortunately created more busy work than valuable challenges for them, and they verbally expressed their disappointment and desire to be challenged, even going so far as to bring algebra problems from an older siblings' math text to class one day. I wanted to change, and I needed an approach that would motivate all my students to excitedly tackle math problems. What instructional strategy is most effective to make math accessible and comprehensible to all students? How do I meet the needs of students who are low performing as well as high-achieving students? No curriculum or math text gives a how-to guide. Differentiated math instruction was the solution to my predicament. WHAT IS DIFFERENTIATED INSTRUCTION? Differentiated instruction is a teaching method used to meet the diverse needs of learners. Teachers implementing this method provide instruction for individuals or groups of students to benefit both those who find academic concepts difficult and those who find them easy. Differentiated classrooms include several common elements: student responsibility (Pettig 2000), student choice (Pettig 2000), peer tutoring (Lawrence-Brown 2004), flexible grouping (Pettig 2000), and modified instruction (Brimijoin, Marquissee, and Tomlinson 2007). Differentiated mathematics instruction ensures successful math teaching when properly applied. Students who are taught through differentiated methods not only learn mathematics effectively, but they also become motivated students who view themselves as successful mathematicians (Lawrence-Brown 2004). Differentiated instruction appeared valid and successful, but would it work in my classroom for my students? DIFFERENTIATED INSTRUCTION IN A REAL CLASSROOM During the 2006-07 school year, I conducted action research with 22 students in my 4th-grade classroom. I focused primarily on five aspects of differentiation: student readiness, flexible grouping, student responsibility, peer tutoring, and modified instruction. Based on student readiness for each math concept, I applied a differentiated teaching model to my instruction. I used an assessment tool, known as glass, bug, mud, to determine student readiness on a daily basis (Brimijoin, Marquissee, and Tomlinson 2007). Glass, bug, and mud refer to the front of a car windshield. * Glass means the student can see through the windshield clearly and has a strong understanding of the math concept. * Bug is a partially covered windshield, indicating the student's understanding is not completely clear, but there is evidence of knowledge of the subject. * Mud refers to a windshield completely covered by dirt; the student shows no understanding of the concept. …