8th Grade, CC3, Unit 7
Slope and Association
Section 1: In this section, you will first create and interpret circle graphs. You will also learn how to make graphs that compare two sets of data. Then, you will use scatterplots and linear graphs to make observations and predictions about the data based on correlations.
Section 2: Here, you will compare ratios and rates using different representations, including numbers, tables, and graphs. You will find out how to measure the steepness of a line on a graph.
Section 3: In this section, you will find equations of lines that fit data and will use them to make predictions based on trends.
line of best fit
y = mx + b
strength of association
constant of proportionality
linear / non-linear form
1. What would a graph of this data look like?
2. Can I make a prediction>
3. Is there a relationship?
4. What is slope?
5. What information is needed to find the equation of a line?
All Methods & Meanings are available in the textbook. For classroom notes and other handouts, talk to your teacher.
8SP1 Construct and interpret scatterplots for bivariate measurement data to investigate patterns of association between two quantities. Describe patterns such as clustering, outliers, positive or negative association, linear association, and nonlinear association.
8SP2 Know that straight lines are widely used to model relationships between two quantitative variables. For scatter plots, that suggest a linear association, informally fit a straight line, and informally assess the model fit by judging the closeness of the data points on the line.
8EE6 Use similar triangles to explain why the slope, m, is the same between any two distinct points on a non-vertical line in the coordinate plane. Derive the equation y = mx for a line through the origin and the equation y = mx + b for a line intercepting the vertical axis at b.
8F3 Interpret the equation y = mx + b as defining a linear function, whose graph is a straight line; give examples of functions that are not linear.
8EE5 Graph proportional relationships, interpreting the unit rate as the slope of the graph. Compare two different proportional relationships represented in different ways.
8SP3 Use the equation of a linear model to solve problems in the context of bivariate measurement data, interpreting the slope and intercept.
8SP4 Understand that patterns of association can also be seen in bivariate categorical data by displaying frequencies and relative frequencies in a two-way table. Construct and interpret a two-way table summarizing data on two categorical variables collected from the same subjects. Use relative frequencies calculated for rows or columns to describe possible association between the two variables.