   # Classifying Plane Figures

Contributor: Elephango Editors. Lesson ID: 10619

Shape up with this lesson! You'll review plane shapes through interactive online and hands-on activities. There is also a worksheet to show your knowledge of shapes.

categories

## Plane Geometry (2D)

subject
Math
learning style
Visual
personality style
Lion
Intermediate (3-5)
Lesson Type
Skill Sharpener

## Lesson Plan - Get It! Look at the images below.

• How many different shapes can you identify in each?

Plane figures are flat figures that can be drawn on a surface, such as squares, rectangles, triangles, and circles.

• Were you able find a lot of them in the images above?

Good job!

• Did you know they're made of line segments and can be closed or open?

• What is a plane?
• What do we call the shapes drawn on a plane?
• What are the 2 types of plane figures?
• How can we tell if a figure is open?
• Is a curve open or closed?
• Is an angle open or closed?
• How can we tell if a figure is closed?
• What is the name of point where 2 sides meet?

Let's practice identifying open and closed figures!

We can classify these figures (sort them into groups) by:

• whether they're open or closed
• the number of sides
• the number of vertices
• whether the side lengths are the same or different

You learned that the place where two sides meet are called vertices. (One is a vertex; two or more are vertices.)

Let's look at some figures, and see how many sides and vertices they have:

Polygons

A flat, closed shape, with straight sides, is called a polygon. Many different shapes are polygons. Their sides may be equal, or not.

• Is a circle a polygon?

No. It is flat and closed, but it doesn't have straight sides.

Rhombus

A rhombus is a flat shape with 4 equal sides.

• Wait, isn't that what we call a square?

Yes, a square is a rhombus with equal angles. But the angles of a rhombus don't have to be equal.

Here's what a rhombus looks like: If you said, "Hey, that's a diamond!" you are correct. A diamond shape is a rhombus.

Trapezoid

Just one more shape to learn, and that is a trapezoid. A trapezoid is a quadrilateral.

• Do you remember what that is?

Yes, it's a 4-sided figure.

A trapezoid's special feature is that it only has one set of parallel sides. The other sides are not parallel. Wow! You learned a lot about plane figures, and even met some strange figures with funny names.

• Are you ready to practice what you learned?

Great! Move on to the Got It? page, where you'll get to draw all these shapes and practice identifying them!

## Elephango's Philosophy

We help prepare learners for a future that cannot yet be defined. They must be ready for change, willing to learn and able to think critically. Elephango is designed to create lifelong learners who are ready for that rapidly changing future.