Lesson objective: Apply understanding of substituting values in for variables and evaluting an inequality in order to solve real-world problems.

This lesson provides an opportunity for students to apply their knowledge and understanding of substituting values for variables and evaluating an inequality to a real-life situation. Students are asked to help Mr. Lee decide how much pizza, juice and cookies he should get for a class party and stay within a budget.

Key Concept students will use:

- The solution of an equation is the set of values that makes the equation true.

Skills students will use:

- Evaluating values in an equation to determine if the set of values makes the equation true
- Identifying equivalent expressions (Grade 6, Unit 8)
- Appling properties of operations to algebraic expressions just as they did to numerical expressions (Grade 6, Unit 8)

Students engage in Mathematical Practice 1 (Make sense of problems and persevere in solving them) as they determine the amount of pizza, juice and cookies Mr. Lee can buy using substitution and evaluating equations.

**Key vocabulary: **

- equation
- evaluate
- expression
- solution
- substitute
- value