**Objective: **

Find sums and differences of mixed numbers with unlike denominators by combining equal-sized pieces that can be easily subtracted or added.

This optional activity can be used before or after Unit 3 lesson 8.

**Math concept addressed:**

In this Guided Collaborative Task, students will use their knowledge and understanding of equivalent fractions to figure out sums and differences of mixed numbers with unlike denominators. Students will figure this out by using two different strategies and creating visual representations with fraction bars.

Under the “Additional materials” tab, you’ll find grid paper that may be used as students visualize mixed numbers.

**Prior knowledge needed: **

Students bring prior knowledge of equivalent fractions and adding and subtracting with unlike denominators. This prior knowledge is extended to using multiple strategies to find sums and differences.

**How students will collaborate:**

Collaboration happens through a collaborative structure called "Each One Pick One". Students will pick one of the two given strategies to defend as a good strategy to use to solve this task. Then they'll switch strategies so that they can get experience with both.

**Mathematical practice featured:**

Students engage in Mathematical Practice 7 (Look for and make use of structure) as they use multiple strategies to find sums and differences using mixed numbers with unlike denominators. Students should notice that in the problem, they may subtract first and then add, or they may add first and then subtract. They should get the same result.

**Key vocabulary:**

- denominator

- equal-sized

- equivalent fraction

- mixed number