Chapter 1 · Revising and improving

Lesson 1.2 · Warm-up revision (2)

Hua's Classroom for Shanghai Maths — One Lesson One Exercise (English edition, pages 3–5).

Grade 3 First Semester Pages 3–5 ECNU Press

Lesson Alignment

How this Shanghai Maths lesson connects to learning goals, Common Core, and Eureka Math.

Learning Objectives

Students will be able to:

  1. 01Calculate mixed +, −, ×, ÷ using the correct order of operations. (Question 1)
  2. 02Use the column method for multi-digit addition and subtraction. (Question 2)
  3. 03Write number sentences using minuend, subtrahend, and difference. (Question 3)
  4. 04Simplify multi-step calculations with order of operations and properties. (Question 4)
  5. 05Solve multi-step application problems with diagrams and tables. (Question 5)
  6. 06Find missing digits and use the division relationship (dividend, divisor, quotient, remainder). (Question 6, 7)

Common Core Standards

CodeStandard (focus for this lesson)
3.OA.D.8 Solve two-step word problems using the four operations. (Question 3, 5, 7)
3.NBT.A.2 Fluently add and subtract within 1000 using strategies and algorithms. (Question 2, 4, 5)
3.OA.A.3 Use multiplication and division within 100 to solve word problems. (Question 5, 7)
3.OA.B.5 Apply properties of operations as strategies. (Question 4)
3.OA.A.4 (related) Determine the unknown whole number in a multiplication or division equation. (Question 7)
4.OA.A.3 (preview / enrichment) Solve multi-step problems; interpret remainders. (Question 7)

Eureka Math Correspondence

Shanghai Maths 1.2 Focus Eureka Math (corresponding)
Question 1 Order of operations (× ÷ before + −) G3 M1 / M3 fluency; properties of operations
Question 2 Column method (standard algorithm) G3 M2 Topics E–F (addition & subtraction algorithms)
Question 3 Minuend / subtrahend / difference language G2 M5 / G3 M2 subtraction relationships
Question 4 Regroup + order of operations G3 M2 strategies; G3 M1 properties
Question 5 Multi-step word problems, tape/bar models, tables G3 M1 / M3 / M7 application problems
Questions 6–7 Missing digits; dividend = divisor × quotient + remainder G3 M1 Topic B (division as unknown factor); remainder language

Core Concepts

Order of operations, column method, division relationship, and reading equations for this lesson.

Order of Operations

When a number sentence has more than one operation:

Step 1
Do multiplication and division first (left to right).
Step 2
Then do addition and subtraction (left to right).

Examples from Question 1:

Number sentenceThinkAnswer
$42 + 15 \div 3$ $15 \div 3 = 5$, then $42 + 5$ $47$
$27 - 4 \times 6$ $4 \times 6 = 24$, then $27 - 24$ $3$
$24 + 0 \div 6$ $0 \div 6 = 0$, then $24 + 0$ $24$
Note: $0 \div 6 = 0$ is allowed. Division by zero (e.g. $6 \div 0$) is not.

Column Method

Line up digits by place value (ones under ones, tens under tens…).

ProblemAnswer
$462 + 6079$$6541$
$10101 - 5872$$4229$
$631 - 79 + 557$ Regroup: $(631 + 557) - 79 = 1188 - 79 = 1109$

Parts of a Division

Use for Question 7.

dividend
474
Dividend
÷
78
Divisor
=
6 R 6
Quotient & remainder
TermMeaningIn this problem
DivisorThe number you divide by$78$
QuotientHow many equal groups (result of division)$6$
RemainderWhat is left over$6$
DividendThe number being dividedunknown

Relationship

$$\text{dividend} = \text{divisor} \times \text{quotient} + \text{remainder}$$

Example: divisor $78$, quotient $6$, remainder $6$:

$$78 \times 6 + 6 = 468 + 6 = 474$$

Reading the Equation (review)

OperationExampleRead as
Addition$5 + 2 = 7$“5 plus 2 equals 7”
Subtraction$5 - 2 = 3$“5 minus 2 equals 3”
Multiplication$5 \times 2 = 10$“5 times 2 equals 10”
Division$474 \div 78 = 6\ \text{R}\ 6$“474 divided by 78 equals 6 remainder 6”

Properties & Theorems (used in Question 4)

1. Commutative property of addition

$$a + b = b + a$$

2. Associative property of addition

$$(a + b) + c = a + (b + c)$$

3. Order of operations with parentheses

Multiply/divide first, or use parentheses to show that step clearly:

$$774 - 9 \times 6 = 774 - (9 \times 6) = 774 - 54 = 720$$

Key Terms & Definitions (Reference)

Quick glossary for Lesson 1.2 language.

TermDefinition
Order of operationsMultiply and divide before add and subtract (left to right in each level).
Column methodVertical calculation with digits lined up by place value.
Number sentence / equationAn equation that shows a calculation.
AddendA number being added.
MinuendThe number you start with in subtraction.
SubtrahendThe number being taken away.
DifferenceThe result of subtraction.
FactorA number being multiplied.
ProductThe result of multiplication.
DividendThe number being divided.
DivisorThe number you divide by.
QuotientThe result of division (how many groups).
RemainderWhat is left after dividing into equal groups.
Commutative propertyOrder can change; result stays the same ($a + b = b + a$).
Associative propertyGrouping can change; result stays the same ($(a+b)+c = a+(b+c)$).

Key Answers

Quick reference for this lesson’s exercise answers.

1. Let’s calculate — $47$, $3$, $30$, $51$, $20$, $70$, $44$, impossible ($24\div0\div6$), $20$.

2. Column method — $6541$;\; $4229$;\; $1109$.

3. $4006-418=3588$;\; $8559+8559=17118$.

4. Step by step — $720$;\; $1489$;\; $166$;\; $2100$.

5. Applications — $420$ boxes; yes ($15$ yuan, has $20$); $370$ m; (a) $720$ orders, (b) $60$ more.

6. $788+126=914$;\; $2593-1384=1209$.

7. Dividend $=78\times6+6=474$.