Similarity 1

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Objective

SWBAT explore similarity through dilation.

Big Idea

What are the important things that happen when a figure is dilated?

Lesson Author

Jeff Li MTP

New York, NY

Grade Level

Eighth grade

Subjects

Math

Geometry

Standards

8.G.A.1

Verify experimentally the properties of rotations, reflections, and translations:

8.G.A.1a

Lines are taken to lines, and line segments to line segments of the same length.

8.G.A.1b

Angles are taken to angles of the same measure.

8.G.A.1c

Parallel lines are taken to parallel lines

8.G.A.2

Understand that a two-dimensional figure is congruent to another if the second can be obtained from the first by a sequence of rotations, reflections, and translations; given two congruent figures, describe a sequence that exhibits the congruence between them.

8.G.A.3

Describe the effect of dilations, translations, rotations and reflections on two-dimensional figures using coordinates.

8.G.A.4

Understand that a two-dimensional figure is similar to another if the second can be obtained from the first by a sequence of rotations, reflections, translations, and dilations; given two similar two-dimensional figures, describe a sequence that exhibits the similarity between them.

MP1

Make sense of problems and persevere in solving them.

MP2

Reason abstractly and quantitatively.

MP7

Look for and make use of structure.

Warm Up

10 minutes

Each day, students complete a warm-up that usually consists of spiraling the previous day's material, in addition to older material. Warm-up problems also sometimes extend lessons that students have encountered before to more unfamiliar contexts.

For a video narrative about how I structure each lesson, and how the warm-up fits in, click here.

Play of the Day

40 minutes

Huddle

10 minutes

For the huddle for this lesson, I like to talk about #9 and #10... it pushes the kids' thinking since they are oriented differently. I also spend a good amount of time on #11, and I ask, "what do you think is a popular WRONG answer choice that kids choose, and why?" It opens up a good discussion.

I usually group students according to the following:

- the front row (6 seats) are reserved for kids who are best served by working with me. These are generally the middle low kids - not necessarily the lowest kids.

- the most struggling students are seated next to a strong tutor, as they require more than small-group attention, they need 1-on-1 tutoring as the lesson goes by.

- most middle students are seated next to a a strong-middle student, to maximize the quality of their discussion.

I think about the entire seating chart in pairs.