Naming Solid Figures

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Objective

The students will be able to name and construct common three-dimensional shapes.

Big Idea

Sticky Math!

Opener

15 minutes

In this lesson students will be building three-dimensional figures with marshmallows and toothpicks to build understanding in naming solid figures.

To begin this lesson I do a quick multiplication fact review with marshmallows as a prize.  I have the students use their whiteboards to answer the questions and give a prize to the first student to raise their whiteboard with the correct answer. I do about 15 facts in order to get students math brains turned on and warmed up. 

Practice

30 minutes

Students will be building three-dimensional figures using marshmallows, toothpicks, and tape.  The toothpicks will represent edges and the marshmallows with represent vertices.  I provide tape so that students can make and edge consisting of more than one toothpick.

I begin by holding one of the wooden solid figures I have.  I circulate the room and start to ask questions to the students about the figure I am holding. 

What do you notice about this figure?

Can you put your answers in terms of the vocabulary we discussed yesterday?

I then have the students try and build the figure.  I don’t give them any directions except for explaining the role of the toothpick, marshmallow, and tape.  I allow the students about 3-5 minutes to work.  Once the students have completed their figure I have them keep it on their desk.

I repeat this process for a few other solid figures.  The figures I use in this lesson are cube, rectangular pyramid, triangular pyramid, and rectangular prism. 

Once all four figures are built I review the figures with the students and I give them the names of each figure.  We compare figures and discuss why the figures have their name. 

Strictly geometrically speaking, the three-dimensional shapes studied in fifth grade fall into two main categories.  There are cylinders and cones.  The cylinder category includes prisms and the cones category includes pyramids.  Spheres and egg-like shapes(ellipsoids) fall into another category.

Although I don’t think it is highly important to focus on these classification schemes it is note-worthy because of the emphasis on classifying two-dimensional shapes within the fifth grade CCSS.

Closer

15 minutes

I wrap up this lesson by viewing a slideshow presentation I made with pictures of real-world objects.  I chose pictures that represented items that students would be easily familiar with. 

For each slide I have students look at the picture for about 5 seconds and then share with their partner what they observe or wonder about the picture.  I give them a minute or so to discuss and thing bring the students back to the whole group.  I ask for volunteers to share their thoughts how to name the three-dimensional shape or shapes they see within the picture.

It is important to address an misconceptions that students may have about the difference between two-dimensional and three-dimensional shapes.  For example, for the slide that contains rubix cube, square would not be an appropriate response.  Students need to be comfortable with using their knowledge in two-dimensional shape classification to aid them in naming three-dimensional shapes.