In earlier lessons, students explored addition and subtraction of fractions in context and out of context. They used diagrams to represent and find the values of sums and differences, and they also reasoned numerically. Students learned that a non-unit fraction can be decomposed—in at least one way—into a sum of other fractions with the same denominator. They recognized adding and subtracting fractions as joining and removing parts that refer to the same whole.

In this lesson, students apply these insights, as well as their knowledge of equivalent fractions from an earlier unit and from grade 3, to find differences of a whole number and a fraction.