This course formalizes and extends middle-school mathematics, deepening students’ understanding of linear relationships. The course begins with a review of relationships between quantities, building from unit conversion to a study of expressions, equations, and inequalities. Students contrast linear and exponential relationships, including a study of sequences, as well as applications such as growth and decay. Students review one-, two-, and multi-step equations, formally reasoning about each step using properties of equality. Students extend this reasoning to systems of linear equations. Students use descriptive statistics to analyze data before turning their attention to transformations and congruency theorems. Equations and figures in the coordinate plane assist in connecting Algebra and Geometry through coordinates. The structure and content of this course naturally guides students to experience mathematics as a rational, beneficial subject which challenges students to critically think through problem situations.