Objective:
To familiarize the student with Geometer's Sketchpad (GSP) using basic triangle construction and measurements of angles.
GA QCC: (none)
Lesson: Introduction to Geometer's Sketchpad (GSP)
NAME: __________________________
1. Click on "point " along side bar. Background of selected item will be dark red.
2. Draw ("click") 3 points on screen in shape of any triangle. Choose "arrow" on side bar. Click mouse on screen to "deselect" all objects.
3. Holding down shift key, click all 3 points (one at a time). (They will be highlighted in bold, black circles.)
4. Using the Pull Down menu across the top, choose "Construct" and then "Segments."
5. Click outside of triangle to "deselect" all objects. Hold down shift key and choose all 3 points, again.
6. Using Pull Down menu, choose "Construct" and then "Polygon Interior." Do NOT deselect.
7. Pull down "Display" and select "Color"; choose a color. The triangle should now be a solid color; click to "deselect."
8. Hold down shift key and choose all 3 points in any order.
9. Pull down "Display" and choose "Relabel Points." In the block "Increasing Part of Label," make sure that "A" is typed in the block. Click on OK and click outside object to deselect. Your triangle should be a solid color, and each point is labeled A, B, and C.
10. Now we measure each angle. To measure a single angle, angle A, hold down shift key and choose BAC or CAB. (Make sure that A is in the middle.) Pull down "Measure" and select "Angle": m<BAC= ______ or m<CAB= _______ will appear on the screen. Repeat this step to measure <B and <C. (Make sure that the middle letter is the angle to measure.)
11. There is a calculator in the software. Now you are going to add the angle measurements. Pull down "Measure" and choose "Calculate." (A calculator will appear on the screen.)
12. Click on "m<BAC" then "+" on the calculator; then click on "m<ABC" and "+"; then click on the last angle and select OK. What sum appears on the screen?____________ Close out calculator by selecting "Cancel" and deselect outside the object.
13. With the mouse, drag on any point of the triangle and move. As the triangle size changes and as the angles change, does the sum change? ________________
14. The following will make the triangle move on its own. Choose "Circle" on the side bar; select a position for the circle center somewhere close to a triangle vertex and drag the mouse so that the circle increases in size until the circumference of the circle touches the nearest vertex. Select the "Arrow" on the side bar and deselect outside the object.
15. Holding down the shift key, click in this order: triangle vertex touching the circle and then click on the circumference of the circle.
16. Pull down "Edit," choose "Action Button,"and choose "Animation." The dialog box will have 3 boxes: "one way," "around circle, " and select "slowly" inside the menu. Click on "Animate." An "Animate" block will appear on the screen; double click on "Animate."
17. As the triangle vertex moves around the circle, do the angles change? _______________ Does the sum of the angles change? ______________
18. Click the mouse to stop the animation.
19. When you have completed this exercise, do not save the GSP file.