Unit 1, Lesson 4
Scaled Relationships
Grade 7
Preparation
Lesson Narrative
In this lesson, students examine corresponding parts more closely, to make a case for whether a figure is or is not a scaled copy of another (MP3).
- Previously students saw that a scale factor relates the corresponding side lengths of a figure and a scaled copy. In this lesson, they notice that corresponding distances not connected by a segment are also related by the same scale factor as corresponding sides.
- Previously students used tracing paper to compare corresponding angles. In this lesson, they use protractors to test their observations about corresponding angles. They verify, in several sets of examples, that corresponding angles in a figure and its scaled copies are the same size.
Practice with the use of protractors helps develop a sense for measurement accuracy and for drawing conclusions from said measurements, such as determining whether or not two angles are the same.
- Explain (orally and in writing) that corresponding angles in a figure and its scaled copies have the same measure.
- Identify (orally and in writing) corresponding distances or angles that can show that a figure is not a scaled copy of another.
- Recognize that corresponding distances in a figure and its scaled copy are related by the same scale factor as corresponding sides.
Let’s find relationships between scaled copies.
Required Preparation
For the digital version of the activity, acquire devices that can run the applet.