Algebra 1 Lesson

From Proportional to Linear: Graphs, Tables, and Equations

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8th grade honorsBTC Style / Thinking ClassroomsCCSS.MATH.8.F.A.370 min
Learning Objective

Students will be able to determine whether a relationship is proportional or non-proportional, represent linear relationships using tables, graphs, and equations, and interpret slope and y-intercept in context.

Lesson Overview

Students progress from identifying proportional relationships through graphs and tables to writing and interpreting linear equations in slope-intercept form, distinguishing proportional from non-proportional linear relationships throughout.

Materials

  • Vertical whiteboards or chart paper
  • Dry-erase markers
  • Random grouping tool
  • Four-quadrant note sheet (printed)
  • Mild/Medium/Spicy practice cards

Scaffolded Task Progression

1Task 1
Here is a graph of two runners' distances over time.


[ Interactive graph / diagram, available in the full lesson ]


Runner A starts at the origin. Runner B starts 10 units ahead. Which runner shows a proportional relationship between time and distance? How do you know from the graph?
2Task 2
Use the same graph from Task 1.


[ Interactive graph / diagram, available in the full lesson ]


For Runner A: make a table of values for . For Runner B: make a table of values for . Then compute the ratio for each runner at . What do you notice?
3Task 3
A different situation: A plumber charges 50 dollars per hour with no additional fees.

1. Write an equation for total cost in terms of hours .
2. Is this relationship proportional? Justify using the equation AND the graph.


[ Interactive graph / diagram, available in the full lesson ]

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