Name:______________________
Date__________________
Hour_____________
Geometer’s Sketchpad Activity
Objectives:
1. Become familiar with using Geometer’s Sketchpad.
2. Learn how to make constructions in Geometer’s Sketchpad.
3. Make conjectures about geometrical relationships by
constructing points, lines, segments, angles and polygons in
Geometer’s Sketchpad.
Getting Started
When you first open Geometer’s Sketchpad, this is the screen you
will see.
Tools Menu
Tip: Before highlighting something, click anywhere in the blank white space
so all previously highlighted items become no longer highlighted.
Exploring Segments
1. Draw a segment and construct a third point on the segment (by
highlighting your segment and going to ‘construct’ and then ‘point
on segment’) in between its endpoints. Label all of your points.
Draw a sketch of your segment and point in the space provided
below.
2. On your screen, measure the length of the entire segment by
highlighting the segment (make sure only the segment is
highlighted) and click on the ‘Measure’ menu (on the top) and
select ‘length.’ Measure the length of all of the segments (there
should be 3). Add your measurements to your sketch above.
3. Manipulate the segment by selecting an endpoint and stretching it
or contracting it. Explain what happens to the measures on your
screen.
4. Manipulate the segment by selecting the point between the two
endpoints and moving it along the segment. Explain what happens
to the measures on your screen.
Exploring Angles
1. Create an angle in your workspace (do this by creating two rays with a
common endpoint.)
2. Create any point on the interior of your angle.
3. Label all points in your drawing including the rays of your angle, the vertex
and the point on the interior of your angle. Make a sketch of your angle
below.
4. Create a segment from the vertex of your angle to the point that’s in the
interior of the angle. Do this by selecting both the vertex and the point on
the interior of your angle, then click on the ‘Construct’ menu (at the top).
Select ‘Segment’. Add the segment to your drawing above.
5. Measure each of the angles – both the smaller ones and the large one as well.
To do this, select a point on one ray, the vertex and a point on the other ray
at the same time, then click on the ‘Measure’ menu (at the top) and select
‘Angle’. (Make sure the vertex is the second point selected!!) The measure
of your angle should appear in your workspace. Record the measure of all
of your angles on your diagram above. Remember to un-highlight all points
before measuring each angle.
6. Select your vertex. Then, select the point on the interior of the original
angle and hold down the mouse key while moving the point around. Make a
conjecture (below) about how the measures of the smaller angles relate to
the larger angle.
Perpendicular Bisector
1. Construct (do not draw or sketch) a segment and its perpendicular bisector.
(think about what it means to be the perpendicular bisector) Make a sketch
of it below and describe how you constructed it. Measure each segment and
angle and add those measurements to your sketch.
Angle Bisector
1. Construct (do not draw or sketch) an angle and its bisector. (think about
what it means to be the angle bisector) Make a sketch of it below and
describe how you constructed it. Measure each angle and add the
measurements to your sketch.
Explore!
Now it’s your turn to just explore! Construct figures that involve different
segments and angles and manipulate your drawings to discover new properties.
Make a sketch of any figures you create and describe how you created the
figure. Also, write down any conjectures you make about the figure.