# Act 01

## Act 01

Approximate Total Time: 25 minutes

Midpoint of a Segment

ACTIVITY OVERVIEW: In this activity we will • • • • Draw a segment Find the midpoint Measure the segment and each half Change the length

This activity allows us to review the basic geometry deﬁnitions of segment and midpoint, while learning to use drawing and measurement tools. We can then explore changes in measurements as we alter the ﬁgure. NCTM Geometry Standard: Analyze characteristics and properties of 2- and 3-dimensional geometric shapes and develop mathematical arguments about geometric relationships.

1
Press A. Move down to the CabriJr APP and press e. Press e, or any key, to begin using the application. Press ! for the F1 menu and select New. (If asked to Save changes? press < e to choose “No.”)

4
Move the cursor until the segment is dashed and ﬂashing then press # for F3 and move down to Midpoint and press e.

5 2
Press @ for the F2 menu. Move to Segment and press e to activate the segment drawing tool. Press e again to mark the midpoint. Press C to exit the Midpoint drawing tool.

6 3
Move the pencil to the desired location of one endpoint and press e. Move to the other endpoint of the segment and press e. Press C to exit the Segment drawing tool. Press % for F5 and move down to Measure and right to D. & Length. Press e.

7
Move until the midpoint is ﬂashing then press e. Move the pencil to an endpoint, and when it is also ﬂashing, press e. The distance from the midpoint to the endpoint is displayed. The hand indicates that the measurement can be moved. Use the arrow keys to move it to a convenient location, and then press C to turn off the hand.

Getting Started with Geometry • cabrijr.com

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Geometry.indb 3

3/6/06 5:07:17 PM

Midpoint of a Segment

8
The measurement tool is still active so return the pencil until the midpoint is ﬂashing. Press e then move until the other endpoint ﬂashes and press e. Move the measurement...