Learning Resource Type

Classroom Resource

Sketchy Dilations

Subject Area

Mathematics

Grade(s)

7, 8

Overview

In this Desmos lesson, students are informally introduced to dilations through experimenting with "sketching machines" that allow them to adjust various parts of a drawing to see the effect on the pre-image. Students are then introduced to similarity as the result of dilation. This activity should be used to help teach a lesson on transformations. This Desmos activity offers sample student responses and a teacher guide.

 

    Mathematics (2019) Grade(s): 8

    MA19.8.24

    Given a pair of two-dimensional figures, determine if a series of dilations and rigid motions maps one figure onto the other, recognizing that if such a sequence exists the figures are similar; describe the transformation sequence that exhibits the similarity between them.

    Unpacked Content

    UP:MA19.8.24

    Vocabulary

    • Translation
    • Reflection
    • Rotation
    • Dilation
    • Scale factor

    Knowledge

    Students know:
    • How to perform rigid transformations and dilations graphically and algebraically (applying coordinate rules).
    • What makes figures similar and congruent.

    Skills

    Students are able to:
    • Use mathematical language to explain how transformations can be used to prove that two figures are similar or congruent.
    • Demonstrate/perform a series of transformations to prove or disprove that two figures are similar or congruent.

    Understanding

    Students understand that:
    • There is a proportional relationship between corresponding characteristics of the figures, such as lengths of line segments, and angle measures as they develop a definition for similarity between figures.
    • The coordinate plane can be used as tool because it gives a visual image of the relationship between the two figures.
    Mathematics (2019) Grade(s): 7 - Grade 7 Accelerated

    MA19.7A.44

    Given a pair of two-dimensional figures, determine if a series of dilations and rigid motions maps one figure onto the other, recognizing that if such a sequence exists the figures are similar; describe the transformation sequence that exhibits the similarity between them. [Grade 8, 24]

    Unpacked Content

    UP:MA19.7A.44

    Vocabulary

    • Translation
    • Reflection
    • Rotation
    • Dilation
    • Scale factor

    Knowledge

    Students know:
    • how to perform rigid transformations and dilations graphically and algebraically (applying coordinate rules).
    • What makes figures similar and congruent.

    Skills

    Students are able to:
    • use mathematical language to explain how transformations can be used to prove that two figures are similar or congruent.
    • Demonstrate/perform a series of transformations to prove or disprove that two figures are similar or congruent.

    Understanding

    Students understand that:
    • there is a proportional relationship between corresponding characteristics of the figures, such as lengths of line segments, and angle measures as they develop a definition for similarity between figures.
    • The coordinate plane can be used as tool because it gives a visual image of the relationship between the two figures.
    Link to Resource

    Resource Provider

    Other
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    License

    License Type

    CUSTOM
    ALSDE LOGO