A. First, choose a picture from the SlopePix web page and paste it into Sketchpad by carefully following these steps:

1. Open a new sketch in Geometer's Sketchpad (GSP).
2. In GSP, turn on the grid (Graph > Grid Form > Square Grid)
3. Construct a point at exactly (0, 10). (Graph > Plot Points > enter 0 and 10 > Plot > Done). This will anchor the upper-left corner of your picture to this point so it won't move.
4. Return to your web browser and right click the picture that you wish to use; select Copy Image.
5. Go back to GSP, be sure the point you plotted is selected, then Edit > Paste Picture. If you want to be sure your picture won't move, pull down Edit > Properties, and UNCHECK the "arrow selectable" checkbox.

B. Next, estimate the slope by hand.

1. Choose a sloped portion of the picture.
2. Using the point tool, draw two points along the slope.
3. Construct the segment connecting the two points.
4. Estimate the rise and the run of the segment by counting the number of squares on the grid between the two points. You may wish to construct the horizonal and vertical segments that represent the rise and run.
5. Estimate the slope by dividing the rise by the run. Is it positive or negative? Use the text tool to type your answer on the screen.

C. Next, calculate the slope with GSP's help.

1. Select each point and pull down Measure > Coordinates for each point. Sketchpad will display the x- and y-coordinates for each point.
2. Use slope formula to calculate the slope of the segment between your two points. (y2 - y1)/(x2 - x1). You may use the Sketchpad calculator (Measure > Calculate). Be sure this calculation is visible on your screen!

D. Now let Sketchpad check your work.

1. Select your segment.
2. Pull down Measure > Slope. The calculated slope will appear on the screen.

E. Find three more slopes.

1. You can either paste in three more pictures, or find three more slopes on your original picture.
2. If you paste in new pictures, change the coordinates of the point you construct in Step A3 so that each of your four pictures will be in a different quadrant of your coordinate plane.
3. Repeat steps B through D three more times.

F. Print your Sketchpad page. Be sure your name is on the page.

G. Look back.

1. Do the slopes calculated by Sketchpad match your calculations? Do they match your estimates? Were your signs (positive or negative) correct?
2. Use the text tool to create a text box. Write a good paragraph summarizing what you did and what you learned. Discuss any mistakes you made and what you learned from them.