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4.3 The Slope is the Thing
10 minutes
The mathematical purpose of this activity is for students to interpret the slope (rate of change) and the intercept (constant term) of a linear model in the context of the data.
Ask students to compare their responses to their partner’s for several scatter plots A, B, C, and D, and decide if both their responses are correct for each scatter plot, even if they are di erent. Follow with whole-class discussion.
Instructional Routines
• Think pair share
What: Students have quiet time to think about a problem and work on it individually, and then time to share their response or their progress with a partner. Once these partner conversations have taken place, some students are selected to share their thoughts with the class.
Why: This is a teaching routine useful in many contexts whose purpose is to give all students enough time to think about a prompt and form a response before they are expected to try to verbalize their thinking. First they have an opportunity to share their thinking in a low-stakes way with one partner, so that when they share with the class they can feel calm and con dent, as well as say something meaningful that might advance everyone’s understanding. Additionally, the teacher has an opportunity to eavesdrop on the partner conversations so that she can purposefully select students to share with the class.
Launch
Arrange students in groups of two. Allow them to work through the problems and use a think pair share to begin the lesson synthesis.
Student Task Statement
1. The scatter plot shows the sale price of several medical items, , and the cost to produce those items, , as well as a line that models the data. The line is also represented by the equation .
Unit 3 Lesson 4: Linear Models
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