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.

Content Standards

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

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

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.

Interdisciplinary Connection(s)

Link to Resource

https://teacher.desmos.com/activitybuilder/custom/5e13560bbefb180dcd92d427

Content Type / Source

Resource Provider

Other

Accessibility

License

License Type

CUSTOM

Custom License Type (URL)

https://www.desmos.com/terms

Comments or Notes

Desmos's mission is to help every student learn math and love learning math. Teachers can explore and enjoy Desmos collections of free digital math activities that include:

Meaningful feedback by showing students what their answers mean, then give them the opportunity to improve their thinking and revise their work.
Collaboration by using devices to connect students, not to isolate them. Students see their classmates' thinking. They ask each other questions and create challenges for each other.
Invites students to solve challenging problems using the tools they already have.

If the teacher does not have an account, he/she will need to create a FREE account. (More information on how Desmos works can be found at Getting Started.)

Once the teacher has selected an activity to run, he/she will need to click on the "Create Class Code" button. This will generate a unique class code and a link to view the dashboard. (More information can be found at Creating a Class Code.) Every new activity will need a new class code in order to start a session. Students cannot start the activity until they have the class code - so sessions can be started days, hours, or mere minutes before you plan to run the activity. When the teacher is ready to have students start, have the students go to student.desmos.com and enter the class code. Although it is not required, Desmos strongly encourages students to sign in with their Desmos Student Account. Signing in allows students to resume and view their past activity work.

Approved Date

2020-07-08

Curated by

yvetteakridge

Design by Adaptive Theme