ABSTRACT
This chapter explores how procedural fluency and conceptual understanding work together to deepen student understanding of fraction addition and subtraction. It further explains that the conceptual understanding of addition and subtraction of fractions is built using visual models, estimation, unit fraction understanding, equivalence, and properties of operations. The chapter focuses on building conceptual understanding and procedural fluency with addition and subtraction of fractions less than 1, and addition and subtraction of improper fractions and mixed numbers. It shows how fraction addition and subtraction concepts can build from thoughtful exploration of equivalence and magnitude. Students begin building the understanding that fractions are composed of unit fractions when they use number lines and visual area models to add fractions with common denominators. They can use their understanding of the commutative and associative properties for addition of whole numbers to support their development of concepts related to adding fractions. These properties improve understanding of the concepts underlying addition of mixed numbers.
