In Module 3, students' understanding of addition and subtraction of fractions extends from earlier work with fraction equivalence and decimals. This module marks a significant shift away from the elementary grades' centrality of base ten units to the study and use of the full set of fractional units from grade 5 forward, especially as applied to algebra. In Topic A, students revisit the foundational grade 4 standards addressing equivalence. When equivalent, fractions represent the same amount of area of a rectangle and the same point on the number line. These equivalencies can also be represented symbolically. In addition, equivalence is evidenced when adding fractions with the same denominator. The sum may be decomposed into parts (or decomposed into an equal sum).