Education Technology

Tight Rope

Published on 06/03/2010

Activity Overview

In this activity, students examine quantities that are linearly related and can be visually represented using a straight-line graph. Students collect distance versus time data using a motion detector and find a model for the time-distance data set.

Before the Activity

  • Connect the computer to the CBL 2™ using the TI connectivity cable

  • Connect CBR 2™ to the DIG/SONIC port of the CBL 2™ unit and set it up to take readings

  • Open a new TI InterActive!™ document
  • See the attached PDF file for detailed instructions for this activity
  • Print pages 8 - 13 from the attached PDF file for your class


  • If you plan to use the EDC quiz as a follow-up, download the file and have it ready to distribute to students via TI-Navigator™.

    During the Activity

    Distribute the pages to the class.

    Follow the Activity procedures:

  • Place the motion detector on the table and collect distance versus time data as the student walks away from the unit
  • Plot a graph of distance versus time
  • Observe that the graph is linear
  • Find b (y-intercept) when x = 0 on the graph
  • Find the slope of the line by guess-and-check method until the slope value models the data well
  • Use values of b and m to form a linear equation of the line in the y = mx + b form
  • Identify two points and calculate the slope using the formula m = (y2 - y1)/(x2 - x1)
  • Compare the slope found earlier with the guess-and-check method and the calculated method
  • Use the linear regression function to get a line that best fits the data and record the linear equation y = ax + b and values of a and b
  • Compare the values of the slope and y-intercept from the linear regression model with the values found experimentally
  • Observe that the linear regression equation is a better fit
  • After the Activity

    Students complete the analysis and answer questions.
    If you are using the TI-Navigator System with the TI-73 you will need the attached .pdf file.
    Review student results:

  • As a class, discuss questions that appeared to be more challenging
  • Re-teach concepts as necessary