G-SRT.1.2

Given two figures, use the definition of similarity in terms of similarity transformations to decide if they are similar; explain using similarity transformations the meaning of similarity for triangles as the equality of all corresponding pairs of angles and the proportionality of all corresponding pairs of sides.

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Formative Assessments
Formative Assessments
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Students are asked to use the definition of similarity in terms of similarity transformations to determine whether or not two quadrilaterals are similar.
Showing Similarity
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Students are given the definition of similarity in terms of similarity transformations and are asked to explain how this definition ensures the equality of all corresponding pairs of angles and the proportionality of all corresponding pairs of sides.
The Consequences of Similarity
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Students are asked to use the definition of similarity in terms of similarity transformations to determine whether or not two triangles are similar.
To Be or Not To Be Similar
Virtual/Hands-on Manipulatives
Virtual/Hands-on Manipulatives
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Assessment Questions
Assessment Questions
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Videos of Expert Instruction
Videos of Expert Instruction
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Don't be a shrinking violet. Learn how uniform scaling is important for candy production.
Making Candy: Uniform Scaling
Use Real Link and Title
Use Real Link and Title
Math Literature
Math Literature
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This lesson provides a real-life context for transformations including rotations, reflections, and translations which are the foundation for how the Common Core State Standards require students to understand congruence and similarity. Rather than begin the lesson by defining the terms and identifying them in the game, the goal is to let students initially describe the movements in their own words and then guide them towards a mathematically precise definition.
How Did They Make Ms. Pac-Man?
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The goal of this task is to examine similarity of triangles from the point of view of proportional sides, showing that this is sufficient to conclude that two triangles are similar.
Similar Triangles
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The task asks students to consider which conditions are enough to constitute a proof and which are not, therefore providing a fertile environment for students to construct arguments leading from assumptions to the desired end result, or explain why no argument could exist.
Are They Similar?
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The goal of this task is to understand similarity as a natural extension of congruence. Two geometric shapes are congruent when there is a sequence of translations, reflections, and rotations which maps one shape to the other.
Congruent and Similar Triangles
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The goal of this task is to study if the analogue of the AA criterion for similarity of triangles holds for different types of quadrilaterals.
Similar Quadrilaterals