Lesson objective: Divide to find the measure of an unknown side of a rectangle.

This lesson helps to build fluency with whole number division. Partial quotients is used here because it further develops a strategy for solving division problems when the equations can't be solved mentally. This work develops students' understanding that the relationship between multiplication and division can be used to solve real-world problems.

Students engage in Mathematical Practice 8 (look for and express regularity in repeated reasoning) as they utilize the multiplication formula used to find area by dividing to solve for a missing side.

**Key vocabulary:**

- area
- inverse