Lesson objective: Calculate sums and differences of fractions in multi-step expressions.

This lesson helps to build towards fluency with addition and subtraction of fractions and mixed numbers whose pieces are different sizes (with unlike units). Multiplication strategies for equivalency are used here because they support fluency in creating like denominators. This work develops students' understanding that naming the sum or difference of two fractions as one number requires rewriting the fractions with same size pieces.

Students engage in Mathematical Practice 2 (Reason abstractly and quantitatively) as they flexibly use different properties of operations to add and subtract fractions with unlike units.

**Key vocabulary:**

- sum
- difference
- equivalent
- decompose
- denominator

**Special materials needed:**

- Students may need fraction tape for intervention.