In a previous lesson, students saw that having a common denominator is useful for adding or subtracting fractions. In this lesson students add and subtract fractions using equivalent expressions where the fractions have the same denominator. Students work with denominators where one is a multiple of the other so they only need to change the denominator in one of the 2 fractions. In each case the numerators are chosen so that either denominator works as a common denominator and students compare different strategies for finding the sum or difference.
- Action and Expression
- Use equivalent expressions to add and subtract fractions with unlike denominators.
- Let’s use equivalent expressions to add and subtract fractions with unlike denominators.
Teacher Reflection Questions
- Would You Rather? (2–5), Stage 3: Compare Units in a Given System (Addressing)
- Compare (1–5), Stage 6: Add and Subtract Fractions (Supporting)