# Spotting Two Dimensional Shapes

13 teachers like this lesson
Print Lesson

## Objective

Students will be able to recognize and draw shapes having specified attributes, such as a given number of angles or a given number of equal faces. Identify triangles, quadrilaterals, pentagons, hexagons, and cubes.

#### Big Idea

Students will be able to identify 2-dimensional shapes and tell the number of vertices and sides.

## To Begin

15 minutes

﻿﻿Before this lesson begins students should already have knowledge of the following vocabulary:

• vertices - corners of the shape where 2 line segments meet to form an angle vertex and sides.docx
• sides - line segments that connect end-to-end

To activate prior knowledge, I display shapes that students have already learned. As I hold up each shape, I ask them to tell me the shape I am holding up.  I ask them do they know any different kind of shapes other than solid figures we have learned about.

Now, I say there are many different kinds of shapes in the world of math.  Each shape has its own special traits.  I ask what would happen to the solid shapes if they were transformed into  2- dimensional shapes. This will help students connect 2- dimensional shapes to what they already know about solid figure shapes.

Then, we compare the similarities and differences between shapes we have learned about  and 2-dimensional shapes.

We used a rectangle and a pentagon to do the comparison.  What pattern do you see? How many sides? Are both shapes completely flat?  How many vertices?

I point out:

2-dimensional shape is completely flat.

My goal is for students to see the similarities and differences between shapes we have already learned about and 2-dimensional shapes, so they will be able to identify 2-dimensional shapes.

This lesson will focus on the following Mathematical Practices:

MP.2. Reason abstractly and quantitatively.

MP.4. Model with mathematics.

MP.5. Use appropriate tools strategically.

MP.7. Look for and make use of structure.

## Model, Listen, and Do Activity!

15 minutes

Material: Shape 1.docx CentimeterDotPa.pdf

In this portion of the lesson I ask students to move to their assigned partner. I explain, that they will be doing a teacher model , and do activity. My students understand that this means they need to focus as I model.

I ask students to draw a two-dimensional shape with 3 sides in the first box.  I provide struggling students with dotted paper, so that they can use the corners to make straight lines. Students who are more on target are allowed to use their rulers.

Teacher Talk:

What is the name of the shape you drew?

Can you explain?

Students seem to understand when describing shapes it is called attributes.

I ask students to draw a two-dimensional shape with 4 sides. I notice students who did not quite get it the first time follow the same process as above. Did anyone draw a rectangle? Did anyone get anything different? Explain? As students are explaining other shapes with 4 sides, I focus their attention to similarities and differences among two-dimensional shapes.

Student Sample

## Collaborate

15 minutes

I quickly review the name of each 2-dimensional shape. (Triangle, Quadrilateral, pentagon, and  hexagon).

As I review the names I hold up each shape in my hand, and  ask students to count aloud as I point to each side of the shape. Then, I ask students to count aloud as I pointed to each vertex of the given shape.

Review:

2-Dimensional shapes have:

• vertices - corners of the shape where 2 line segments meet to form an angle
• sides - line segments that connect end-to-end

My goal is to build some background knowledge before we began working together on correctly identifying the shape and the number of sides and vertices.

Next I bring students to the carpet area and ask them what do they notice about 2-dimensional shapes?  Their response should be: it is flat.  If students are unable to notice that 2-dimensional shapes are flat. Tell them explain that if a blanket is placed on top of a 2-dimensional shape (like a sheet of paper), the blanket will lay flat.

(Please demonstrate, so that students can visually see that you can identify 2-dimensional shapes because they are flat.)

Then, we discuss how to determine the correct number of vertices and sides there are for each given shape.  My goal is for them to be able to correctly identify and tell the correct number of vertices and sides of two dimensional shapes on their own.

As I pick up each shape, I ask students to count the number of sides and vertices of each shape.  Then, I ask students how do you know it is a 2-diminsional shape?

I repeat this activity until a level of understanding is reached.