Chapter 4 · Dividing by a one-digit number

Lesson 4.12 · Unit price, quantity and total price (1)

Hua's Classroom for Shanghai Maths — One Lesson One Exercise (English edition, pages 93–95).

Grade 3First Semester Pages 93–95ECNU 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. 01Relate unit price, quantity, and total price.
  2. 02Find any one quantity given the other two.
  3. 03Compare unit prices (whose rubber is cheapest?).

Common Core Standards

CodeStandard (focus for this lesson)
3.OA.A.2Interpret whole-number quotients.
3.OA.A.3Multiply/divide within 100 to solve word problems.
3.OA.B.5Apply properties of operations.
3.OA.B.6Understand division as unknown-factor.
3.OA.C.7Fluently multiply and divide within 100.
3.OA.D.8Two-step word problems.
3.MD.A.2*(related)* Measure/solve with money contexts.

Eureka Math Correspondence

Shanghai MathsFocusEureka Math
Multiplicative compareUnit rate ideasG3 M1 / M3

Core Concepts

Introduce the relationship among unit price, quantity, and total.

Price Triangle

$$\text{total price} = \text{unit price} \times \text{quantity}$$

So unit price $= \text{total} \div \text{quantity}$, quantity $= \text{total} \div \text{unit price}$.

Find Any One

Boxes of apples: cost of 8 boxes; apples in 8 boxes; rubbers bought with given money.

Compare Unit Prices

Different children buy different packs — compute price per rubber and compare.

Key Terms & Definitions (Reference)

Quick glossary for this lesson.

TermDefinition
Unit pricePrice of one item.
QuantityNumber of items.
Total priceUnit price × quantity.

Key Answers

Quick reference for this lesson’s exercise answers.

1. Mental calculation

  • $21\times3=63$,\; $7200\div6=1200$,\; $13\times7=91$,\; $80\div5=16$
  • $20\times4=80$,\; $90-26=64$,\; $16\times2=32$,\; $180+70=250$
  • $270\div9=30$,\; $40\times2-40=40$,\; $49\div7+8=15$,\; $56-48\div3=40$

2. Formulas

  • Unit price × quantity = total price
  • Total price ÷ unit price = quantity
  • Total price ÷ quantity = unit price

3. Fill in the table

ProductUnit priceQuantityTotal
Pencil case$6$$7$$42$
Pen$34$$10$$340$
Water-colour marker$9$/box$100$$900$

4. Multiple choice

  1. A
  2. C
  3. B

5–8. Application / calculate

  1. $6$ cans $432$ yuan;\; with $8$ more: total $1008$ yuan
  2. $90$ yuan for $3$ boxes;\; $192$ apples in $8$ boxes
  3. $6\times660=3960$;\; $660\div6=110$;\; dividend $3223$
  4. Pack of $9$ is better ($27<36$)

9–11. Enhancement

  1. Xiao Qiang (cheapest per rubber)
  2. $66$ metres
  3. $16$th tree