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 CIGS = Corner for Interactive Geometry Software

The Geometer's Sketchpad
Spirograph Lab, Parts 1 & 2

Mike Riedy

TOC || Page 2 || Page 3 || Page 4 || Intro Lab

Part 1: Preliminary Setup

Most of this lab is based on the animation done in the GSP Introductory Lab. The animation must be duplicated for use throughout the entire lab. Let's begin by recreating our old friend Roger.

Start with a new sketch. Draw a medium-sized circle in the center of your sketch. Label the point on the circle "Radius control 1". You should note that this first point controls the size of the circle - hence the name.

Now highlight the circle (not the center) and choose "Point On Object" from the CONSTRUCT menu. A new point should appear on the circle. Find its label and change it to "Roger". Highlight Roger and the center of the circle and have the computer construct a segment connecting the two. Change the color of this segment, Roger, and the circle to blue.

Now Roger is back and we are ready to roll. We will use this basic construction throughout the entire lab, calling it the "Roger construction".

Part 2: Tracings As Artwork

Highlight Roger and the circle, in that order, and choose "Animate" from the sub-menu under the "Action Button" under the EDIT menu. Make sure your choices for the animation match those in the picture below.

The name of the circle is not important; however, the "one way" and "quickly" are crucial. Once your screen matches, click on "Animate". A button labeled "Animate" should then appear on your sketch. You can change the label on the button by using the text tool. Change it to "Animate Roger".

Before animating Roger there are a few more things to do to make things interesting. Highlight the radius of Roger's circle and choose "Trace Segment" from the DISPLAY menu. Then choose "Dashed" from the sub-menu "Line Weight" under the DISPLAY menu. Now animate Roger by double-clicking on the button "Animate Roger".

Describe what you see:

Let's look at some interesting 'artsy' things you can do with GSP. Use the point tool to put a point anywhere outside the circle. Have the computer construct the segment connecting the new point and Roger. Make the segment red and dashed . Highlight the segment and choose "Trace Segment" from the DISPLAY menu. Now animate Roger. Funky, isn't it?

What shape does the tracing of the segment look like?

Now put two or three other points outside the circle and connect them to Roger. Follow the same procedure as above using a different color for each segment connected to Roger and then animate Roger. Save this to your disk as "Roger Animation".

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