Explanation

2D (two-dimensional) objects are flat shapes. They have:

• Length and width

• No thickness

• Measured by area

Examples:

• Square, rectangle, triangle, circle

3D (three-dimensional) objects are solid shapes. They have:

• Length, width, and height

• Take up space

• Measured by volume and surface area

Examples:

• Cube, rectangular prism, sphere, cylinder, cone, pyramid

Key differences:

• 2D shapes are flat

• 3D shapes have depth

• 2D → area

• 3D → volume & surface area

Quiz: 2D vs. 3D Objects

1. How many dimensions does a rectangle have?

2. Which measurement is used for 3D objects: area or volume?

3. Is a circle a 2D or 3D shape?

4. Name one example of a 3D object.

5. Which has thickness: a square or a cube?

Answer Key

1. Two

2. Volume

3. 2D

4. Answers may vary (cube, sphere, cylinder, etc.)

5. Cube