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## Construct a Solid

3-5
1

Students construct physical models of geometric solids.

For this lesson, students will need to work with a partner and construct one or more of the geometric solids out of coffee stirrers and twist ties, straws and pipe cleaners, toothpicks and gumdrops, or other available supplies. For example, a tetrahedron built out of straws is shown:

Students should use the Geometric Solids Tool to help them build the physical model.

Each pair of students should record how you constructed each solid in a table, such as the one below.

This is a meaningful activity for students. You may wish to start with simple polyhedra, such as a cube or a tetrahedron. Students can rotate their solid, count the faces, corners, and edges and compare their results with the ones in the table.

 Shape How did you construct the shape? Tetrahedron Cube Octahedron Dodecahedron Icosahedron Irregular Polyhedron

Draw attention to the fact that these constructions look like the transparent shapes in the computer program. They may wish to look at their shape on the computer, using the transparent tool.

Early finishers can build shapes of their own. As in the previous part of the lesson, they should record the shape and information about the shape in their tables.

Remind students that their constructions are only representations of the geometric solids. Students should note the lack of actual "faces" in their representations, since they are simply open-air spaces.

• Geometric Solids Tool
• Construction tools, such as coffee stirrers, twist ties, straws, pipe cleaners, toothpicks, gumdrops, etc.

Extension

Move on to the last lesson, Making A Shape Jacket.

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### Getting to Know the Solids

3-5
Students are introduced to some of the basic polyhedra. Students explore the shapes of the faces of these solids.

### Study the Solids

3-5
In this interactive geometry investigation, students explore geometric solids and their properties. Specifically, students count the number of faces, edges, and corners (vertices) in various solids.

### Looking for Patterns

3-5
Students discover Euler's Formula, a way of calculating the number of faces, edges, and vertices of geometric solids.

### Making A Shape Jacket

3-5
Students identify which geometric solids can be made from given nets. Students also create nets for common geometric solids.

### Learning Objectives

Students will

• Analyze characteristics and properties of three dimensional geometric shapes.
• Construct physical models of geometric solids.

### NCTM Standards and Expectations

• Investigate, describe, and reason about the results of subdividing, combining, and transforming shapes.
• Build and draw geometric objects.