Lesson 1: What are Scaled Copies?

Let’s explore scaled copies.

1.1: Printing Portraits

Here is a portrait of a student. Move the slider under each image, A–E, to see it change.

GeoGebra Applet XsnFAdq7

  1. Which images are most like the original? Which are least like the original? Explain your reasoning.
  2. Some of the sliders make scaled copies of the original portrait. Which of the Portraits A–E do you think are scaled copies? Explain your reasoning.
  3. What do you think “scaled copy” means?

1.2: Scaling F

On the top left is the original drawing of the letter F. There are also several other drawings.

  1. Identify all the drawings that are scaled copies of the original letter F drawing. Explain how you know.
  2. Examine all the scaled copies more closely, specifically, the lengths of each part of the letter F. How do they compare to the original? What do you notice?
  3. On the grid, draw a different scaled copy of the original letter F.

GeoGebra Applet zxRa9YuY

1.3: Pairs of Scaled Polygons

Your teacher will give you a set of cards that have polygons drawn on a grid. Mix up the cards and place them all face up.

  1. Take turns with your partner to match a pair of polygons that are scaled copies of one another.
    1. For each match you find, explain to your partner how you know it’s a match.
    2. For each match your partner finds, listen carefully to their explanation, and if you disagree, explain your thinking.
  2. When you agree on all of the matches, check your answers with the answer key. If there are any errors, discuss why and revise your matches.
  3. Select one pair of polygons to examine further. Use the grid below to produce both polygons. Explain or show how you know that one polygon is a scaled copy of the other.

GeoGebra Applet TynXHZv3


What is a scaled copy of a figure? Let’s look at some examples.

The second and third drawings are both scaled copies of the original Y.

However, here, the second and third drawings are not scaled copies of the original W.

The second drawing is spread out (wider and shorter). The third drawing is squished in (narrower, but the same height).

We will learn more about what it means for one figure to be a scaled copy of another in upcoming lessons.

Practice Problems ▶


scaled copy

scaled copy

A scaled copy of a figure is a figure in which every length in the original figure is increased or decreased by the same scale factor.