Lesson 8
Multiply 2 Twodigit Numbers
Lesson Purpose
Lesson Narrative
Previously, students used placevalue reasoning to decompose a factor in a multiplication expression to multiply numbers up to fourdigit by onedigit numbers. In this lesson, they apply these ideas to multiply 2 twodigit numbers. They reason about why it is helpful to decompose both twodigit numbers by place value. As students analyze the connections between expressions and diagrams, they recognize that partial products in which the factors are either singledigit numbers or multiples of 10 can be found mentally, making the rectangular diagram a useful tool for multiplying twodigit numbers.
 Action and Expression
 MLR8
Learning Goals
Teacher Facing
 Multiply 2 twodigit numbers using place value understanding and properties of operations.
Student Facing
 Let’s multiply 2 twodigit numbers.
Required Preparation
Lesson Timeline
Warmup  10 min 
Activity 1  20 min 
Activity 2  15 min 
Lesson Synthesis  10 min 
Cooldown  5 min 
Teacher Reflection Questions
In a future lesson, students will be analyzing partial products from rectangular diagrams and making connections to the traditional algorithm notation. How do rectangular diagrams support this thinking?
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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Additional Resources
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