Unit 8

Properties of Two-dimensional Shapes

Unit Goals

Unit Narrative

In this unit, students deepen their understanding of the attributes and measurement of two-dimensional figures.

Prior to this unit, students learned about some building blocks of geometry—points, lines, rays, segments, and angles. Students identified parallel and intersecting lines, measured angles, and classified angles based on their measurement. In this unit, they apply those insights to describe and reason about characteristics of shapes.

In the first half of the unit, students analyze and categorize two-dimensional shapes—triangles and quadrilaterals—by their attributes. They classify two-dimensional shapes based on the presence or absence of...

Section A

Section Goals

Section Narrative

This section prompts students to consider different ways of looking at two-dimensional figures: by the number of sides, length of sides, size of angles, presence of parallel or perpendicular lines, and symmetry. Students examine these attributes in figures, classify the figures by the attributes, and explain their classifications. For example, they identify quadrilaterals as parallelograms if they have two pairs...

Let’s sort flat figures.

Let’s sort and analyze triangles.

Let’s sort and identify quadrilaterals.

Let’s describe symmetry in flat figures.

Let’s draw some figures that have lines of symmetry.

Let’s use what we know about attributes of figures to create drawings.

Section A Practice Problems

to access Section Checkpoints.

Section A

Let’s sort flat figures.

Let’s sort and analyze triangles.

Let’s sort and identify quadrilaterals.

Let’s describe symmetry in flat figures.

Let’s draw some figures that have lines of symmetry.

Let’s use what we know about attributes of figures to create drawings.

Section B

Section Goals

Section Narrative

In this section, students apply their knowledge of geometric attributes to reason about measurements in various two-dimensional figures. They find the perimeter of figures where the side lengths are all given. Then they move on to cases where the side lengths are not explicitly given but can be deduced based on information about the figure.

Later, students are given the...

Let’s find the perimeter of different shapes.

Let’s find the unknown lengths in figures.

Let’s investigate symmetry and perimeter in folded figures.

Let’s find angle measurements in figures with line symmetry.

Let’s use symmetry to think about sports.

Section B Practice Problems

to access Section Checkpoints.

Section B

Let’s find the perimeter of different shapes.

Let’s find the unknown lengths in figures.

Let’s investigate symmetry and perimeter in folded figures.

Let’s find angle measurements in figures with line symmetry.

Let’s use symmetry to think about sports.

to access End-of-Unit Assessments.

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Properties of Two-dimensional Shapes

Unit Goals

Unit Narrative

Section Goals

Section Narrative

Section A Practice Problems

Section Goals

Section Narrative

Section B Practice Problems

Unit 8 Resources

About Unit 8

Other Resources

Section Goals

Section Narrative

Section A Practice Problems

Section Goals

Section Narrative

Section B Practice Problems