Work in this section introduces students to situations that can be represented by lines with a non-positive slope. Students explore a situation where one quantity decreases at a constant rate in relation to a second quantity, and similar situations, in order to compare rates that increase, decrease, or do not change.

Next, students recall earlier work using slope triangles in...

In this section, students examine systems of linear equations and solve them by finding pairs of values that make both equations true. They begin by revisiting what it means when points are on or off a graphed line in relation to the equation represented by the line. Then, they recognize that a system of equations can be solved by finding...

Work in this section takes previous learning with proportional relationships and looks at it from a grade 8 perspective in preparation for work with linear relationships. Students begin the section by observing features of graphs, such as labels and scaling of the axes, to make sense of situations. Students continue to explore the importance of scaling when studying graphs drawn...

Work in this section builds on students’ understanding of proportional relationships to introduce linear relationships that are not proportional.

Students begin by determining the height of stacks of cups to make predictions. The relationship in this situation has a constant rate of change, making it linear. But since the graph of the line representing the situation does not go through...

In this section, students look at organizing data from two variables. They interpret and create scatter plots to visualize numerical data and look for basic trends.

Then students look more closely at associations between variables using scatter plots. They informally assess the fitness of linear models, attempt to draw their own linear models, and interpret slope of a linear model...

In this section, students turn their attention to bivariate categorical data. They interpret two-way tables and turn them into tables showing relative frequencies. They informally determine whether the relative frequencies suggest an association between the categorical variables by comparing the percentages within different categories.