Big Idea: Describing the 2-D faces of 3-D solids

Expectations:

E. Spatial Sense E1. Geometric and Spatial Reasoning: describe and represent shape, location, and movement by applying geometric properties and spatial relationships in order to navigate the world around them

• Geometric Reasoning: E1.2 construct three‐dimensional objects, and identify two‐dimensional shapes contained within structures and objects

teacher background

Students may benefit from prior experience with:

• sorting 2-D shapes and 3-D solids using a single attribute

• identifying 2-D shapes

• using geometric language to describe 2-D shapes and 3-D solids

KEY CONCEPTS:

• Each face of a three-dimensional object is a two-dimensional shape. Often, a shape is identified by the number of sides it has. Common shapes on faces of three-dimensional objects are triangles, rectangles, pentagons, hexagons, and octagons.

• While the number of sides often determines a shape’s name, this does not mean, for example, that all triangles look the same even though they all have three sides. Triangles can be oriented differently and have different side lengths, and yet still be triangles.

Note

• Constructing three-dimensional objects helps build understanding of attributes and properties of two-dimensional shapes and three-dimensional objects.

LOOK-FORS:

• Are students using one type of solid to build their towers, or are they using a variety of solids?

• Do students use geometric and spatial language in their descriptions (e.g., “The solid with 4 rectangular faces is on top”)?

• Do students use gestures to support their descriptions of the towers?

• Are students using descriptions that differentiate one solid from other solids?

Go on a gallery walk to look at some of the towers. As students are describing them, listen for geometric and spatial language (e.g., faces, rectangles, beside). Watch for students who use gestures to support their descriptions. Ensure that students see the connection between 3-D solids and the shapes of their 2-D faces. For each of the solids used, make a list of the shapes of its faces. Have students find/identify 3-D objects in the world around them that have parts similar to a given 2-D shape (e.g., rectangle: computer screen; circle: frying pan; square: building block).

Highlight for Students

• We can identify a 3-D solid by describing its 2-D faces.

• We can use solids to build 3-D towers

Accommodations: Students use two or three solids that are very different, such as cubes and cylinders.

Extension: Students use a greater number of solids to make the towers.

Combined Grades Extension: Students build more complex structures (e.g., castle, animal), and then describe them for their partners to build.

Assessment tools are available by logging into your Mathology account and searching for Activity Card 11: Geometric Relationships: Faces of Solids - Grade 1.

SEL Self-Assessments (English) and Teacher Rubric

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