Lesson objective: Use equations to solve problems.

Students bring prior knowledge that mathematical relationships can be represented with expressions and that they can use those expressions as they use numbers from 6.EE.B6.C. This prior knowledge is extended to use equations to solve problems as students calculate perimeter using equations. A conceptual challenge students may encounter is understanding how to use equations to solve problems.

This work helps students deepen their understanding of equivalence because equations show a relationship between expressions. We can use the relational meaning of the equal sign to find a missing value in an equation.

Students engage in Mathematical Practice 1 (Make sense of problems and persevere in solving them) as they work to create and solve equations to find missing side lengths in order to find the perimeter of the chicken coop.

**Key vocabulary:**

- equation
- expression
- perimeter
- substitute
- variable