2D and 3D Shapes

2D Shapes: Flat Shapes All Around Us#

A 2D shape is a flat shape. The "2D" stands for "two-dimensional" — it has length and width, but NO depth or thickness. If you draw a shape on paper, it is a 2D shape!

Properties of 2D Shapes#

To describe a 2D shape, we look at its sides and corners (also called vertices).

• Sides are the straight lines that make up the border of the shape.
• Corners (or vertices) are the points where two sides meet.

Common 2D Shapes#

Circle

• Sides: 0 (it has a curved edge, not straight sides)
• Corners: 0
• Examples: wheels, coins, clock face, plates

Triangle

• Sides: 3
• Corners: 3
• Examples: slices of pizza, road signs, triangular sandwiches

Square

• Sides: 4 (all sides are equal)
• Corners: 4 (all corners are right angles — perfectly square)
• Examples: tiles, crackers, sticky notes

Rectangle

• Sides: 4 (opposite sides are equal)
• Corners: 4 (all right angles)
• Examples: doors, books, window panes, dollar bills

Pentagon

• Sides: 5
• Corners: 5
• Examples: home plate in baseball, the Pentagon building

Hexagon

• Sides: 6
• Corners: 6
• Examples: honeycombs, snowflakes (sort of!)

Shapes in the Real World#

Look around your classroom and home — you will see 2D shapes everywhere!

• The face of a clock: circle
• A window: rectangle
• A roof outline: triangle
• Floor tiles: squares or rectangles
• Road signs: triangles, hexagons, pentagons

Sorting 2D Shapes#

You can sort 2D shapes by different attributes:

• Number of sides: shapes with 3 sides, 4 sides, 5 sides, etc.
• All sides equal / not all equal: squares vs. rectangles
• Has curved sides / straight sides only