Discover how to create an equation from a given slope and point in this activity called “The Value of Toys."
Three exercises are included, each focusing on a different toy and how its value has changed over the years. Students will take given information, answer questions, create their own questions, create an equation, and create a graph. I recommend doing one exercise as a class, and then let students work through the next two exercises in partners.
Last students experiment with point-slope form to create an equation. They should produce the same equations they created in the three exercises.
I like to let students discover their own strategies before I tell them formulas. Point-slope form is a great shortcut, but students should understand the concept of creating an equation from a slope and point instead of just plugging in numbers.
This activity also has a focus on vocabulary, asking students to use the following words in explanations: initial value, rate of change, independent variable, and dependent variable.
Common Core Standards:
Construct a function to model a linear relationship between two quantities. Determine the rate of change and initial value of the function from a description of a relationship or from two (x, y) values, including reading these from a table or from a graph. Interpret the rate of change and initial value of a linear function in terms of the situation it models, and in terms of its graph or a table of values.
Write a function that describes a relationship between two quantities.*
Create equations in two or more variables to represent relationships between quantities; graph equations on coordinate axes with labels and scales.
Thank you for your interest in this produce from Rise over Run.
Check out these other great graphing resources:
Growing Graphing Bundle
What’s the Equation? (from 2 points)