CCSS.Math.Content.8.EE.B.5
The standard
Graph proportional relationships, interpreting the unit rate as the slope of the graph. Compare two different proportional relationships represented in different ways.
Common Core State Standards for Mathematics · Expressions and Equations
What this standard means
Students need to connect a proportional relationship to a straight line through the origin. They should find the unit rate from a table, equation, graph, or verbal situation, then explain it as the slope of the line.
Mastery looks like comparing two relationships even when they are shown in different forms, such as a graph and an equation. Students often get stuck reading slope from a graph, mixing up x and y, or comparing total amounts instead of rates.
Ways to teach it
- Hands-on activity: Use tape on the floor and timed walking trials, then graph distance versus time and label the slope as speed.
- Discussion or writing prompt: Which is faster, y = 3x or a line through (0,0) and (4,10), and how do you know?
- Quick assessment: Give one table, one graph, and one equation, then ask students to circle the greatest unit rate and show work.
- Real-world connection: Compare two cell phone plans with cost per gigabyte, using one graph and one equation.
Plan a lesson for CCSS.Math.Content.8.EE.B.5
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Related standards
- CCSS.Math.Content.7.RP.A.2
Recognize and represent proportional relationships between quantities.
- CCSS.Math.Content.7.RP.A.2b
Identify the constant of proportionality (unit rate) in tables, graphs, equations, diagrams, and verbal descriptions of proportional relationships.
- CCSS.Math.Content.7.RP.A.2a
Decide whether two quantities are in a proportional relationship, e.g., by testing for equivalent ratios in a table or graphing on a coordinate plane and observ...
- CCSS.Math.Content.7.RP.A.2c
Represent proportional relationships by equations.