Decomposing Rectangles

This video tutorial teaches how to decompose rectangles using benchmark numbers. It begins with an introduction to benchmark numbers and their role in making estimates. The tutorial then demonstrates decomposing various arrays and rectangles, such as 3x9, 4x8, 12x4, and 4x7, using benchmark numbers like 5 and 10. Each decomposition is shown step-by-step, illustrating how the original area is divided into smaller parts while maintaining the same total area. The lesson concludes by summarizing the decomposition process using benchmark numbers.

What is the area of a 3x9 rectangle before decomposition?

• 18 square units

• 45 square units

• 27 square units

• 36 square units

When decomposing a 4x8 rectangle, which benchmark number is used?

• 6

• 4

• 5

• 3

How is a 12x4 rectangle decomposed using benchmark numbers?

• Into 8x4 and 4x4

• Into 9x4 and 3x4

• Into 6x4 and 6x4

• Into 10x4 and 2x4

What is the total area of a 4x7 rectangle after decomposition?

• 36 square units

• 32 square units

• 28 square units

• 24 square units

Which benchmark number is used to decompose a 4x7 rectangle?

• 4

• 3

• 5

• 6