Prism or Pyramid?

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SWBAT identify prisms and pyramids by the faces, bases, edges, and vertices and by their nets.

Big Idea

Understanding solids and nets helps develop the concepts of volume and surface area


10 minutes

Students will be writing in their notes what they feel is the difference between 2-D and 3-D objects.  They are instructed to use drawings and examples to help explain the difference.  I chose to do this because I wanted to assess prior understanding or hook them in for today’s learning.  I’m going to give students some time to write and think about 2-D vs 3-D objects.  Students can then pair up to discuss their thoughts on the subject.

Tools:  DO NOW question.

3-D Vocabulary

15 minutes

I will be discussing the vocabulary of three dimensional objects.  This vocabulary is important because they will need to identify prisms and pyramids by their faces, bases, edges, and vertices.  Once we go over the vocabulary we will be doing some practice at identifying the solids by these features.  We will also be looking at their nets to help us see the characteristics easier.

SMP1: making sense of solids requires an understanding of vocabulary

Tools: Prism or Pyramid notes and power point

Talking about Prisms

15 minutes

In this section we will be focusing on prisms.  The students need to know that a prism has 2 parallel bases, it’s named by its base and the faces are made up of rectangles.  Students have difficulty understanding the difference between a face and a base.  Tell students that when they identify a prism, they should look for the two polygons that are the same.  This will tell you the name of the prism.  The net is useful here because they can actually see the 2 bases and the rectangular bases.  It is also easier to count the edges and vertices in the net, but I would show them how to do it with the solid too. For each example, I would ask the student how the solid got its name?  They should be able to point out that they see 2 polygons that are the same and it is named by these two polygons.

We will also be looking at a cylinder which is a special type of prism.  Ask students why this can’t be classified as a prism and why it can?  They should say that it does have 2 parallel bases , but it does not have rectangular faces.

(SMP5: using their vocabulary as a tool to help them identify solids)

Talking about Pyramids

15 minutes

In this section, I will be talking with the students about pyramids.  It is important for them to know that a pyramid has 1 base and triangular faces.  A pyramid is also named by its base. For each example, there is a visual of the solid and the net to help with the explanation.  Again, we will be looking at the edges, vertices, faces and bases. Continue to ask the students how the solid got its name.  The hardest pyramids for students to understand are the difference between a triangular pyramid and a rectangular pyramid. They struggle with this because of the triangular sides.  It’s important for students to see there is 1 rectangular base and the faces are triangles in a rectangular pyramid whereas, the triangular pyramid is made up of all triangles.

We will also be looking at a cone which is a special type of pyramid.  The cone has 1 circular base.  Some students may also see that the there is one vertex.  Ask students why this can’t be classified as a pyramid and why it can? Students should say that it does have one base, but it is missing the triangular faces.  They can also say that it is a pyramid because it does meet at one vertex. 

Independent Practice

15 minutes

Allow students time to work on the 8 independent practice problems.  These are in their notes.  Go over this as a whole group so students can make changes as needed.  As you work through each problem, they will be required to explain how they know their answer is correct.  Having students support their decisions is implementing SMP3.  As students finish the problems, they can do a HUSUPU to find a partner to share their solutions.

Tools:  Prism or Pyramid power point and notes. 


15 minutes

The students will be using a Venn Diagram (SMP5) to compare and contrast prisms and pyramids.  I will be looking for students to say:

Prisms:  2 bases, rectangular faces

Pyramids: 1 base, triangular faces, meets at a point

Similarities:  3-D shapes, have faces, bases, edges, and vertices.

Knowing the characteristics of solids will help when finding volume and surface area.

For the next question, I want the students to be thinking about the cone and how it is like a pyramid and how it is different. 

Cone is like a pyramid because it has 1 base and meets at a point.  It is different from a pyramid because it does not have a triangular face.

Tools:  prism or pyramid notes.