Chapter 2 · Multiplying by a one-digit number
Lesson 2.4 · Multiplying a two-digit number by a one-digit number (1)
Hua's Classroom for Shanghai Maths — One Lesson One Exercise (English edition, pages 23–24).
Lesson Alignment
How this Shanghai Maths lesson connects to learning goals, Common Core, and Eureka Math.
Learning Objectives
Students will be able to:
- 01Use arrays to see two-digit × one-digit as equal groups. (Question 1)
- 02Split a two-digit factor into tens + ones and multiply. (Question 2)
- 03Calculate products such as $36 \times 6$, $17 \times 5$. (Practice)
- 04Begin recording with the column method.
Common Core Standards
| Code | Standard (focus for this lesson) |
|---|---|
| 3.NBT.A.3 | Related place-value strategies. |
| 3.OA.B.5 | Distributive property. |
| 3.MD.C.7 | Area / arrays related to multiplication. |
Eureka Math Correspondence
| Shanghai Maths | Focus | Eureka Math |
|---|---|---|
| Distributive | Tens + ones | G3 M3 Topic E–F |
| Arrays | Equal groups | G3 M1 / M3 |
Core Concepts
Multiply a two-digit number by a one-digit number by splitting into tens and ones.
Split the Two-Digit Factor
$$13 \times 6 = (10 + 3) \times 6 = 10 \times 6 + 3 \times 6 = 60 + 18 = 78$$
$$21 \times 7 = 20 \times 7 + 1 \times 7 = 140 + 7 = 147$$
Array / Area Model
Count stars/dots in an array, or draw tens and ones bars, then multiply each part.
Toward Column Method
Vertical form records the same split: multiply ones, then tens, then add (or use the standard algorithm with regrouping).
Key Terms & Definitions (Reference)
Quick glossary for this lesson.
| Term | Definition |
|---|---|
| Distributive property | $(a+b)\times c = ac + bc$. |
| Array | Rows and columns of equal groups. |
| Partial product | Product of one part (tens or ones). |
Key Answers
Quick reference for this lesson’s exercise answers.
Key answers
- $10×6=60$, $3×6=18$, $60+18=78$; so $13×6=78$
- Calculate: $7×74=518$; $2×93=186$; $26×8=208$; $89×6=534$; $64×9=576$; $5×54=270$
- Fill brackets: (1) $0,1,2,3,4,5,6,7,8,9$ (2) $3$
- Applications: (1) No ($45×9=405<452$) (2) $72$ pupils
- Compare: $>$; $<$; $<$; $<$
- Formation: $9×11=99$ people