Wyoming Math 8.F.4b
The Standard
Apply the concepts of linear functions to real-world and mathematical situations. Determine the slope and the y-intercept of a linear function given multiple representations, including two points, tables, graphs, equations, and verbal descriptions.
2023 Wyoming Mathematics Content and Performance Standards · Use functions to model relationships between quantities.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students find the slope and y-intercept from two points, a table, a graph, an equation, or a short story. They use those values to write and explain a linear rule.
What Mastery Looks Like
- Given points (2, 9) and (5, 15), a student finds a slope of 2 and a y-intercept of 5. They can check both values on a graph and explain what they mean in a situation.
Common Misconceptions
- Students may divide the change in x by the change in y, or mistake the table value at x = 1 for the y-intercept. On a graph, they may choose the first visible point instead of the point where x = 0.
How to Assess It
- Exit ticket: A bike rental costs $11 for 2 hours and $20 for 5 hours. Find the hourly rate and starting fee, then write an equation.
Lesson moves
Ways to Teach It
Give pairs graph paper and coordinate cards (1, 7) and (4, 16); have them plot the line and mark its y-intercept.
Ask students why 8 is not the y-intercept for a line through (1, 8) and (3, 14), then have them find the intercept.
Play a card match with y = 2x + 3, a table with (0, 3) and (1, 5), and a graph through both points.
Show a taxi fare sign: $4 pickup plus $2 per mile; ask students to sketch the cost graph and label slope and intercept.
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Printable 8.F.4b Worksheet
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Related Standards
- 8.F.4d
Interpret the meaning of the slope and the y-intercept of a linear function in the context of the situation.
- 8.F.4c
Construct a function in slope-intercept form that models a linear relationship between two quantities.
- 8.EE.8c
Solve simple real-world and mathematical problems leading to two linear equations in two variables given y = mx + b form with integer solutions.
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