Lesson 8
Multiply 2 Two-digit Numbers
Lesson Purpose
Lesson Narrative
Previously, students used place-value reasoning to decompose a factor in a multiplication expression to multiply numbers up to four-digit by one-digit numbers. In this lesson, they apply these ideas to multiply 2 two-digit numbers. They reason about why it is helpful to decompose both two-digit numbers by place value. As students analyze the connections between expressions and diagrams, they recognize that partial products in which the factors are either single-digit numbers or multiples of 10 can be found mentally, making the rectangular diagram a useful tool for multiplying two-digit numbers.
- Action and Expression
- MLR8
Learning Goals
Teacher Facing
- Multiply 2 two-digit numbers using place value understanding and properties of operations.
Student Facing
- Let’s multiply 2 two-digit numbers.
Required Preparation
Lesson Timeline
| Warm-up | 10 min |
| Activity 1 | 20 min |
| Activity 2 | 15 min |
| Lesson Synthesis | 10 min |
| Cool-down | 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: Two-digit Factors (Addressing)
- Compare (1–5), Stage 3: Multiply within 100 (Supporting)