Digital Skills: Developing Online Assessment Skills in Everyday Classroom Activities Western Reserve Public Media

Line of Best Fit with Desmos
This lesson will help the student create a scatter plot using Desmos and then have them working with the graphing tools on the calculator.

I can:
  • I can find the equation for a line of best fit
Tech Skills:
  • Learn to Use Desmos graphing calculator

  • Click and drag graphing manipulation

Materials and Resources:

Any technology,  phones, tablets or computers

Desmos teacher account (free)

Using Desmos worksheet
Grade Level:
  • 8th-9th Grade
Subject Area:
  • Math 8 or Algebra 1


Activity 1

  1. Bellwork: Pick a problem to have the students find the equation of the line from two points

  2. After a quick review of slope and y-intercepts, distribute the worksheet and technology

  3. Using a projector or Smart Board, complete the “learn the skill section of the worksheet with the students.

  4. Work through how to create a table.

  5. adjusting window range to see data

  6. type in “y=mx+b”  and use the sliders to find the line of fit. Have the students calculate the slope by hand to check the technology.



Activity 2

  1. Do the “you do it” section independently to clarify students’ understanding.

  2. Walk around to help the students with the activity. They need to fill in the information on their worksheets



Practice Activity

Have the students complete the last question on the Using Desmos worksheet.


8.SP.1 Construct and interpret scatter plots for bivariate measurement data to investigate patterns of association between two quantities. Describe patterns such as clustering; outliers; positive, negative, or no association; and linear association and nonlinear association. (GAISE Model, steps 3 and 4)

8.SP.2 Understand that straight lines are widely used to model relationships between two quantitative variables. For scatter plots that suggest a linear association, informally fit a straight line, and informally assess the model fit by judging the closeness of the data points to the line. (GAISE Model, steps 3 and 4)

8.SP.3 Use the equation of a linear model to solve problems in the context of bivariate measurement data, interpreting the slope and intercept. For example, in a linear model for a biology experiment, interpret a slope of 1.5 cm/hr as meaning that an additional hour of sunlight each day is associated with an additional 1.5 cm in mature plant height. (GAISE Model, steps 3 and 4)

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