# Intro to 3D Figures and Cross-Sections - What shape do you see?

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## Objective

Students will be able to correctly name prisms and pyramids with varying base shapes, and identify the 2D shape formed by the intersection of a plane and prism or pyramid.

#### Big Idea

Put on your funny glasses â we are going 3D! Students will use technology to manipulate and discover cross-sections.

## Launch

10 minutes

OpenerAs students enter the room, they will immediately pick up and begin working on the opener –Instructional Strategy - Process for openers.  This method of working and going over the opener lends itself to allow students to construct viable arguments and critique the reasoning of others, which is mathematical practice 3.

Learning Target:  After completion of the opener, I will address the day’s learning targets to the students.  In today’s lesson, the intended targets are “I can identify prisms and pyramids and correctly name them by the shape of their base” and “I can identify the shape of a cross-section formed by a plane and a prism or pyramid.”

## Explore

45 minutes

Intro to 3D Figures and Cross-Sections Notes:  This lesson is an introduction to 3D figures, and will be mostly teacher led.  However, I will employ student input and prior knowledge when completing the fill in the blank sections of the guided notes. The instructional portion of the lesson will begin with notes on prisms – properties of right prisms, and naming prisms.  After completing the notes, I will ask students to name the prisms pictured on the notes/smartboard.  Next, I will conduct a drawing lesson!  It is a bummer to complete a word problem with  no picture, especially if you cannot draw a picture yourself, so I will give the students a mini-art lesson on drawing rectangular and triangular prisms - being able to draw the figures will help them to employ their mathematical tools later on - art! (MP 5). Next, we will move onto pyramids, and complete the notes on properties of pyramids and naming pyramids.  Again, I will ask that students work in their table groups to correctly name the pyramids show on the notes/smartboard. Then, I will conduct another mini-lesson on drawing pyramids.

Table Challenge:  Next, students will compete in a quick table challenge where they are asked to identify a figure.  I have placed 6 figures on a die, and using the random number generator (in smartboard) I will call on groups to identify the figure.  Groups who answer correctly will be rewarded.

More Instruction: After the table challenge, we will move into a discussion on cross-sections.  Being that this is a difficult concept for students to visualize, I am going to use the site, Interactivate: Cross Section Flyer to aid in our discussion.  Using the scroll bars on the website, you can change the number of lateral faces – so I will use this feature to adjust the pyramid and prisms to have rectangular bases, as those are the cross sections we will focus on.  Using the questions on the guided notes, I will adjust the figure on the applet and allow tables time to discuss their answers.  I will then ask tables to respond with what they see/think about the questions.

## Summarize + Homework

5 minutes

Class Discussion:I will wrap up the lesson by asking two questions: “What is a cross-section?” “What different 2D cross sections might we see when a plane intersects with a rectangular pyramid?” I will take student volunteers to discuss the answers to the questions.

HomeworkI will pass out the homework, and students will take the last couple minutes of class to look over the homework and ask any questions that they may have regarding the assignment. Philosophy on Homework