Lesson 2: Fitting Linear Models & Trend Lines
Duration of Days: 3
Lesson Objective
Informally fit a straight line to a scatter plot showing a linear association, and assess its model fit by analyzing how closely data points cluster around the line.
What makes a trend line a "good fit" or a "bad fit" for a scatter plot?
How can we strategically place a straight line so that it fairly represents the overall direction of the data?
Why do some scatter plots cluster tightly around a trend line while others are loosely scattered, and what does that tell us about the relationship?
CCSS.MATH.CONTENT.8.SP.A.2
Description/Purpose: Students transition from observing raw patterns to active mathematical modeling. Students learn to draw informal trend lines through bivariate data, balancing the points above and below the line, and critically evaluate the strength and reliability of their model based on point dispersion.
DOK Level: 3 (Strategic Thinking / Model Analysis)
Students often mistakenly believe a trend line must connect the very first data point to the very last data point, rather than passing through the center of the data.
Provide transparent plastic rulers so students can physically shift and manipulate a trend line across a printed scatter plot before drawing i.t
Exit tickets