Summer Lesson Building (Geometry: Naming Basic Geometric Figures)

So, I put in for a presentation at the Florida Lab School Drive-in Conference and managed to get accepted. My session title is “Creating Need in the Mathematics Classroom” and is centered on an approach I started to focus on last year in my curriculum. I’ll give more details as I really dig into making my presentation. But in order to help my presentation, I need to start building lessons that lend themselves to helping create my presentation. So here we go:

Although it’s technically not a standard, the first topic we’ll discuss in geometry is how to name basic geometric figures. My students need to be proficient in naming points, lines, rays, line segments, angles, etc.; otherwise, they won’t succeed in Geometry.

So I figure there’s two options in how to present this to students.
Option 1: I can tell my students how to name figures. If they ask my why, I’ll tell them because I said so…or someone said so some time ago. I can hear my students falling asleep already. I can hear them saying “who cares?” I can see them struggling to remember how to name geometric figures. I need a better option.

Option 2: I can create a need for naming geometric figures. Here’s how:

We’ll start with this slide:
1.1 The Building Blocks of Geometry_3

I’ll ask one student to pick a point and not tell anyone which one they chose. I’ll then ask them to describe which point they chose to someone else on the other side of the room without using any physical cues. My hope is that this will be a giant pain in the rear for my students.

Then I’ll show them this slide:
1.1 The Building Blocks of Geometry_4

I’ll ask them to repeat the process. I’m betting they’ll have an easier time.

To really emphasize my point (and to practice the whole writing and communicating thing), I’m going to give them a partner project:

One person in the partnership will get this:
1.1 The Building Blocks of Geometry_7

They’ll get three minutes to write a set of instructions to have their partner recreate this picture. Once the instructions are made, their partner will have to use this:
1.1 The Building Blocks of Geometry_4
and recreate the picture.

My hope is that they’ll fail miserably, and this activity will create a need for them to find a better way to quickly and efficiently name geometric figures.

We’ll start with lines. I’ll ask a student to pick a line:
1.1 The Building Blocks of Geometry_8
Then, they’ll have to describe which one they picked to a fellow student.
1.1 The Building Blocks of Geometry_9
They’ll decide this is easier. I’ve purposely set this up to where they’ll need two points to describe which line they chose. Once they’ve made this decision (and only when they’ve decided how to name the line), I’ll help them create that definition:

1.1 The Building Blocks of Geometry_10

By now, I think my students will have gotten the point. We’ll discuss how to extend this idea to line segments and rays. To finish, we’ll go back to this activity:

1.1 The Building Blocks of Geometry_13

I’ll have one student write a set of instructions and their partner will recreate the picture.

My hope is that this lesson design will create a need for naming geometric figures. The way we name figures is not arbitrary, and hopefully my students will discover that.

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2 thoughts on “Summer Lesson Building (Geometry: Naming Basic Geometric Figures)

  1. Love it, Cory! Consider writing this up and submitting it to CPALMS. We can suggest it, when appropriate, to teachers using MFAS in the Instructional Implications sections of tasks.

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