# Categories and Characteristics of 3D Solids

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## Objective

SWBAT differentiate between 3d solids.

#### Big Idea

Students develop the characteristics of polyhedrons.

## Do Now

10 minutes

The Do Now Problem problem is a review of two previous concepts, finding the area of an irregular polygon and finding the area of a shaded region.  I will encourage students to work independently but use their notes.

Students will need to find the area of the larger rectangle.  In order to find the area of the inner polygon, they will have to divide it into 3 rectangles.  Students may have difficulty finding the area of these rectangles, because the dimensions for all the sides are not directly given.

## Important Vocabulary

5 minutes

It is helpful to students that as they learn the vocabulary that will be used in the lesson, they have a visual to associate it with. As I review the vocabulary, I will use a cardboard box to demonstrate the terms.

Polyhedron - a 3 dimensional shape that has flat surfaces (faces) and straight edges

Face - a flat surface

Edge - A line formed by two faces.

Vertex - The point where 2 or more edges meet. (corner)

Nets - two-dimensional drawings that represent the surface area of three-dimensional shapes

## Mini Lesson

15 minutes

Rather than give students the characteristic that differentiate between prisms and pyramids, they will develop them.  I will present students with the Prisms vs Pyramids Pictures.  Students will have 5 - 10 minutes to discuss the differences between prisms and pyramids with their group.  They should write down their ideas, which will be shared with the class.

After 10 minutes, the class will come together again and I will ask groups to share out their thoughts.  Each group will share 2 characteristics.  The discussion will be student led, but I will interject if I feel students are moving in the wrong direction.

After students have thoroughly discussed the differences and characteristics of prisms and pyramids, I will share a formal list of them.

Categories & Characteristics of 3-D Solids:

Prisms

1.  Have 2 congruent, polygon bases which are parallel to one another

2.  Sides are rectangular

3.  Named by the shape of their base

Pyramids

1.  Have 1 polygon base with a vertex opposite it

2.  Sides are triangular

3.  Named by the shape of their base

## Class Activity

10 minutes

The purpose of this Prism/Pyramid Sort Activity is to reinforce the new vocabulary and the characteristics of prisms and pyramids.  The activity is a Smartboard sort activity, but it can be adapted for classrooms without a Smartboard.  I will randomly call students to the board to choose a polyhedron, place it in the correct category, and explain the characteristics that place it in that category.

Most students may know the category of the polyhedron, but may have difficulty describing its' characteristics.  If a student has difficulty with the characteristics, he may choose another student to help him.

This activity will help all students, even those who are not called to the board.  Students will have the opportunity to hear the characteristics of polyhedrons described in a variety of ways.

## Lesson Summary

5 minutes

I will review the lesson, by having students make real world connections to polyhedrons.

Where, in the real world, have you seen polyhedrons?