GSP Introduction Exploration

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Objective: Learn basic operations of The Geometer’s Sketchpad.

Making Mistakes

You are bound to make some mistakes while working with the GSP. There are a couple of simple ways to correct a mistake.

  • Simply press and hold down the command key (that's the one with the funny little apple on it), then press the "Z" key. This combination, referred to as "Apple Z," will undo, in reverse order, any previous steps you made.
  • Choose "Undo" under the EDIT menu.

The Toolbox

As GSP starts up, you will see a picture with the words "The Geometer's Sketchpad" in the center of the screen. Click once anywhere to clear the picture. On the left side of your screen you will see six different squares with different objects in them. These objects are called the tools. The five most commonly used tools and their names are at the top of this page. The area to the right of the tools is called the window. We are going to examine how to use each of the five tools. Note that the software is very particular. If you are, for instance, in the circle tool mode, then you can only draw circles. If you want to draw line segments or select part of your drawing, then you will have to select that tool first.

The Circle Tool:


Select the circle tool by using the mouse to position the arrow over the circle tool and click once. To draw a circle, move the mouse to the right onto the sketch window. Press and hold the mouse button while moving the mouse. A circle should appear. Draw several circles of different size. (Five or six should suffice.) Now practice erasing them by using "Apple Z" or "Undo." One by one the circles should disappear. Now draw three circles of different sizes that fit on the screen.

The Select Tool:


Choose the select tool (sometimes called the translate tool). When you press and hold the select tool three other pictures appear. For now, make sure you are using the first one with the arrow only. Move onto the window and highlight a circle by moving the arrow close to a circle until the arrow becomes horizontal. When the arrow is horizontal it means the arrow is pointing to something. Try to avoid the point on the circle; you'll need that shortly. 1. With the arrow horizontal, hold down the mouse button and move the mouse around. What happens?

Arrange the circles from smallest to largest so that they look like a snowman.

2. By using the select tool, how can you change the size of the circle you have already drawn? (Hint: paragraph above.)

The Point Tool:


Select the point tool - it looks like a dot. Using this tool is very simple: wherever you click, a point appears. Use the point tool to put eyes, nose, mouth, and buttons on your snowman. (You can also put snowflakes all around your snowman.)

The Segment and Line Tool:


The segment tool allows you to draw straight objects. When you press and hold the segment tool three other pictures appear.

3. Sketch each of the other tools and give their names.

Off to the side of your snowman you are going to practice drawing one of each of the three types of straight objects. To draw a straight object, click and hold the mouse button while dragging in the direction you want your object to go. Try drawing one horizontally. What happens when you hold down the SHIFT key while drawing a segment? (Hint: move the endpoint around in a circle.)

Now use the segment tool to put arms and hands on your snowman. (You could also draw the ground and a put a hat on the snowman.)

The Labeling Tool:


When you draw anything GSP gives it a name called a label. Sometimes, however, the label is invisible. Every point, circle, and segment you have drawn on your snowman has a label - even if you can't see it.

Using Sketchpad

Let's see what the program labelled your snowman's nose. Choose the labelling tool from the toolbox on the left of the screen (it looks like a little hand). Move the hand close to the nose of your snowman. When you are pointing at the nose the hand will turn black. Click once and a letter should appear.

4. What is the label for your snowman's nose?

Click on the nose again to make the label disappear. The labelling tool actually serves two purposes: labelling tool and text tool. You have already seen what the labelling does. The text tool allows you to write whatever you want anywhere on the sketch. To put your name on the snowman, find an empty place on your picture and move the labelling tool there. Click and hold the mouse button while dragging diagonally. A box should appear. This is called a text box. Type some text of your choice in the text box. (Your name would do.)

Optional: Printing and Saving:

Let's print the snowman to see how he looks. Before you print, however, make sure your picture is complete with all the necessary parts. Your name and the date should also be on the sketch. Once all this is complete choose "Print" under the FILE menu. Your snowman will pop out at one of the printers in the room.

A New Sketch:

You now need a new, blank sketch to work with. Choose "New Sketch" under the FILE menu. What is the keyboard shortcut for starting a new sketch?


The most important thing in GSP is how to highlight objects. This is your way of telling the computer, "I'm talking about this object." To highlight you must use the select tool. The computer puts little black squares on the object to highlight a straight object or a circle. A point is highlighted when it looks like a bulls eye.

  • On your new sketch, draw several points. Notice that the last point you drew is highlighted.
  • Draw a circle and two segments that start outside the circle and pass through it.
  • Use the select tool to move the circle just a little bit but still intersecting the segments.

What if you want to move more than one thing at a time? Version 4.0 will allow you to select multiple objects by clicking on them in turn. Make sure you do not click outside the figures. This will deselect everything. Now highlight the circle and one of the segments. Move them away from the second segment so that the second segment and the circle no longer intersect.

Hiding Objects:

Very seldom when using GSP will you delete objects. Instead you will hide them. Look through the menus to find the "Hide" command.

5. What menu was it under? What is the keyboard shortcut?

Highlight the circle and hide it using either the menu or the keyboard shortcut. The circle should disappear. Suppose you really didn't want the circle to be gone because you need it after all. To bring it back you need to use the "Show All Hidden" command under the DISPLAY menu. This will bring back the circle.


Later we will look at properties of transformations, but for now let's look at the basics.

  • Start with a new sketch.
  • Draw a triangle and place a single point somewhere outside the triangle.

6. Describe how you constructed the triangle.

7. There is another way to construct a triangle. How?

  • Highlight only the single point and choose "Mark Centre" under the TRANSFORM menu. What is the keyboard shortcut for marking centre? You can also accomplish this by double-clicking on the point (a little bulls eye should appear around the point for a fraction of a second).
  • Change the select tool to the rotation tool.
  • Highlight all parts of the triangle.
  • Drag the triangle.

8. What happens?

  • Change the rotation tool to the dilation tool.
  • Now try dragging the triangle.

9. What happens when you try to move the triangle closer to and farther away from the point?

The select tool is sometimes called the translate tool.

10. Define the three words translate, rotate, and dilate.

  • Start with a new sketch.
  • On the left half of the sketch draw a small smiley face and a vertical line just to the right of it. Feel free to add some colour and make your smiley face one solid colour.
  • Highlight the line and choose "Mark Mirror" under the TRANSFORM menu.
  • Highlight your entire smiley face and choose "Reflect" under the TRANSFORM menu.

11. Now try moving one of the eyes on the left smiley face. What happens to the eye on the smiley face at the right?

Handin: A sheet with answers to all questions.