Wyoming Math 8.F.4d
The Standard
Apply the concepts of linear functions to real-world and mathematical situations. Interpret the meaning of the slope and the y-intercept of a linear function in the context of the situation.
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 use a line, table, or equation to describe how two quantities change together. They explain the slope as a change per unit and the y-intercept as the amount when the input is zero.
What Mastery Looks Like
- A student can read a graph or equation and name the starting amount and rate, with units. They can use those numbers to predict an output and explain whether it makes sense in the situation.
Common Misconceptions
- Students may swap a flat fee and a per-unit rate, or give a slope without units. Some read the y-intercept as the amount at one unit instead of zero, or mistake a negative slope for a negative starting amount.
How to Assess It
- Exit ticket: A bike rental costs $8 plus $3 per hour. Write an equation, explain what 8 and 3 mean with units, and find the cost for 4 hours.
Lesson moves
Ways to Teach It
Use play money to build taxi fares of $3 plus $2 per mile for 0, 1, and 2 miles.
Ask: On a graph of water draining from a tank, what do the negative slope and y-intercept mean?
Have pairs match cards showing graphs, equations, and stories for three different starting amounts and rates.
Post a mock phone plan of $15 monthly plus $4 per gigabyte; have students write an equation and label both numbers.
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Printable 8.F.4d Worksheet
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Related Standards
- 8.F.4b
Determine the slope and the y-intercept of a linear function given multiple representations, including two points, tables, graphs, equations, and verbal descrip...
- 8.F.4a
Understand that the slope is the constant rate of change and the y-intercept is the point where x = 0.
- 8.F.4c
Construct a function in slope-intercept form that models a linear relationship between two quantities.
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