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What's My Line?

Student Worksheet 2




Name __________________________      Period_______      Date_______________



In this lesson you will create a new line, interpret the meaning of the slope and y-intercept of your line, write a linear equation in slope intercept form and compare graphs with different slopes.

  1. You will create a new line while your partner operates the calculator. Once you like the line that you have walked, trade places with your partner so he/she can create a graph. Set the CBR up as you did in the previous lesson. Move in front of the CBR until you are satisfied with the graph. Sketch the graph below. To the right of the graph, describe the motion that you used to create the graph.

  2. What is the y-intercept of your graph? _________

  3. What is the significance of the y-intercept? ________________________________________________

  4. Using the TRACE key, select two points on your graph that you will use to compute the slope of your line. Write the coordinates of the two points below. Be careful not to round off too much. It is suggested that you round off to the nearest thousandth. Directions for Storing Values into Variables

    ( ________, ________ )
            		 ( ________, ________ )
    x1 y1 x2 y2

  5. To find the slope use the formula: (y2 - y1) / (x2 - x1). The slope of the line is ______.

  6. Using the slope-intercept form of a line, write the equation of your line. ______________________.

  7. Type the equation into the Y= editor of the graphing calculator. When you press GRAPH you should see the line graph on the same screen as the data points. Does the equation fit the data? __________

  8. If you need to make any changes to the equation, make them and re-write the equation and explain what you needed to change. ________________________________________________________________________

  9. You can use your equation to predict various distances that you could walk if you kept the same pace. Using your algebraic model, how far would you have walked if you continued for 25 seconds? _________ 2 minutes? _________.

  10. Do you think that your model would be reasonable for walking 30 minutes? Why or why not? __________________________________________________________________________________________

  11. Compare your equation with the one of your partner. Who walked further in 10 seconds? _________ (remember that you comparing total distance, not where you ended up)

  12. Write down your slope and your partner's slope. _____________      ____________
    Does the person who walked faster have the larger slope or smaller slope? ___________ Explain. __________________________________________________________________________________________

  13. Predict what the slope of the line would be if you walked twice as far in the same 10 seconds. _________

  14. Interpret the meaning of a slope of 3/5 in this situation. _________________________________________

  15. If you changed your starting position and walked at the same rate, how would the two graphs compare? ______________________________________________________________________________________

  16. If you have time during this class period, try walking to create a negative slope.


EXTENSION to Worksheet #2

Create a graph with the CBR similar to the one to the right. Your graph should clearly show three different slopes. Fit a piecewise function to the graph. You can enter each "piece" into Y1, Y2, and Y3. Remember that each graph will require a separate domain statement.


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Updated June 2000