Chapter 5 · Let's practise geometry

Lesson 5.7 · Areas of rectangles and squares (1)

Hua's Classroom for Shanghai Maths — One Lesson One Exercise (English edition, pages 124–126).

Grade 3First Semester Pages 124–126ECNU 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. 01Find areas in $\text{cm}^2$ by counting $1\ \text{cm}^2$ squares.
  2. 02Use area = length × width for rectangles.
  3. 03Solve problems (pool, largest square from a rectangle).

Common Core Standards

CodeStandard (focus for this lesson)
3.MD.C.5Recognize area as attribute.
3.MD.C.6Measure area by counting unit squares.
3.MD.C.7Relate area to multiplication/addition.

Eureka Math Correspondence

Shanghai MathsFocusEureka Math
Rectangle areal × wG3 M4

Core Concepts

Move from counting squares to the rectangle/square area formula.

Count cm²

Each small square is $1\ \text{cm}^2$; count to find the area.

Length × Width

$$\text{area of rectangle} = \text{length} \times \text{width}$$
$$\text{area of square} = \text{side} \times \text{side}$$

Rectangle Problems

Length $40\ \text{cm}$, $10\ \text{cm}$ longer than width; pool length twice width; cut largest square from $12\ \text{cm}$ craft paper.

Key Terms & Definitions (Reference)

Quick glossary for this lesson.

TermDefinition
Square centimetre ($\text{cm}^2$)Area of a $1\ \text{cm}$ by $1\ \text{cm}$ square.
Length / widthSides of a rectangle.

Key Answers

Quick reference for this lesson’s exercise answers.

1. $16\,\mathrm{cm}^2$ ($4\times4$); $15\,\mathrm{cm}^2$ ($3\times5$).

2. $24$; $24$; $25\,\mathrm{cm}^2$.

3–6. $405\,\mathrm{cm}^2$; $1200\,\mathrm{cm}^2$; $1250\,\mathrm{m}^2$; square $144\,\mathrm{cm}^2$, remaining $60\,\mathrm{cm}^2$.

7. T/F — ✕; ✕; ✕; ✕; ✕.

8–9. $3$ rectangles ($1\times12$, $2\times6$, $3\times4$); remaining $72\,\mathrm{cm}^2$.