Lesson 9
Recording Partial Products: Onedigit and Three or Fourdigit Factors
Lesson Purpose
Lesson Narrative
In previous lessons, students used diagrams to represent multiplication of a onedigit number and a whole number of up to four digits. They learned to decompose larger factors by place value and used diagrams and corresponding expressions to support them in finding partial products. In this lesson, students learn an algorithm for keeping track of partial products that come from multiplying the digits of the factors. This algorithm that uses partial products lays the foundation for the standard algorithm for multiplication.
Students engage in quantitative and abstract reasoning (MP2) as they relate the partial products in a diagram and in an algorithm. Because this lesson offers an initial exposure to the new notation, students are not required to use an algorithm that uses partial products to multiply. They can rely on other methods they have learned so far.
 Action and Expression
 MLR8
Activity 1: An Algorithm for Noah
Learning Goals
Teacher Facing
 Multiply multidigit whole numbers by onedigit numbers using an algorithm that uses partial products.
Student Facing
 Let’s analyze and try an algorithm that uses partial products.
Required Preparation
CCSS Standards
Addressing
Lesson Timeline
Warmup  10 min 
Activity 1  20 min 
Activity 2  15 min 
Lesson Synthesis  10 min 
Cooldown  5 min 
Teacher Reflection Questions
Suggested Centers
 Number Puzzles: Multiplication and Division (4–5), Stage 1: Twodigit Factors (Addressing)
 Compare (1–5), Stage 3: Multiply within 100 (Supporting)
Print Formatted Materials
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