Chapter 1 · Revising and improving

Lesson 1.3 · Warm-up revision (3)

Hua's Classroom for Shanghai Maths — One Lesson One Exercise (English edition, pages 6–7).

Grade 3 First Semester Pages 6–7 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:

01Recall vertices, faces, and edges of a cuboid and cube. (Question 1)
02Describe square properties and why a square is a special rectangle. (Question 1)
03Choose suitable units and convert among grams/kilograms, hours/minutes/seconds. (Question 1)
04Read an analog clock and tell time using o'clock, quarter past, half past, and quarter to. (Question 2)
05Classify triangles (acute, right, obtuse) and reason about angles. (Question 2, 3, 6)
06Solve multi-step application problems involving packing and distance. (Question 3, 4)

Common Core Standards

Code	Standard (focus for this lesson)
3.MD.A.1	Tell and write time to the nearest minute; read analog clocks. (Question 2)
3.MD.A.2	Measure and estimate liquid volumes and masses; solve problems involving mass. (Question 1)
3.G.A.1	Understand that shapes in different categories may share attributes. (Question 1, 3)
3.OA.A.3	Use multiplication and division within 100 to solve word problems. (Question 3, 4)
3.OA.D.8	Solve two-step word problems using the four operations. (Question 4)
4.MD.A.1 (preview)	Know relative sizes of time units; express hours in minutes. (Question 1)
4.G.A.1 / 4.G.A.2 (preview)	Draw/identify angles; classify triangles; angles formed by clock hands. (Question 2, 3, 6)

Eureka Math Correspondence

Shanghai Maths 1.3	Focus	Eureka Math (corresponding)
Question 1	3-D solids; square; units & conversion	G2 M8 / G3 M2 measurement; G3 M7 geometry attributes
Question 2	Read analog clock; angle between hands (e.g. half past three)	G3 M2 telling time; G4 M4 angle measure (preview)
Question 3	True/false & multiple choice on triangles	G3 M7 shape attributes; G4 M4 preview
Question 4	Application: packing, distance on a path	G3 M1 / M2 multi-step word problems
Questions 5–6	Count shapes / classify triangles in a figure	G3 M7 composing / decomposing shapes

Core Concepts

Solid shapes, square properties, measurement units, and triangle types for this lesson.

Cuboid & Cube

Solid	Vertices	Faces	Edges	Figure
Cuboid (rectangular prism)	$8$	$6$	$12$
Cube	$8$	$6$ (all squares)	$12$

Vertices, faces & edges

On any cuboid or cube, look for these three parts:

Vertex

A vertex is a corner where edges meet.

Face

A face is a flat side of the solid.

Edge

An edge is a line where two faces meet.

A cube is a special cuboid where every face is a square. It still has $8$ vertices, $6$ faces, and $12$ edges.

Square Properties

A square has 4 equal sides.
All 4 angles are right angles.
Therefore a square is a special rectangle (and a special rhombus).

Units & Conversion

Mass

1\ \text{kg} = 1000\ \text{g} = 1\,000\,000\ \text{mg}

Length

1\ \text{km} = 1000\ \text{m} = 100\,000\ \text{cm} = 1\,000\,000\ \text{mm}

Time

1\ \text{hour} = 60\ \text{minutes} = 3600\ \text{seconds}

Choose units that fit the situation (weight → kg; distance → km or m; short time → minutes; small mass → grams or milligrams).

How to Read a Clock

An analog clock has two hands on a numbered face. Read the minute hand first, then the hour hand.

Hour hand

Shorter and thicker. It shows the hour and moves slowly as minutes pass.

Minute hand

Longer and thinner. Each number on the clock face stands for 5 minutes.

Say	Minute hand points to	Time
O'clock	$12$	$:00$
Quarter past	$3$	$:15$
Half past	$6$	$:30$
Quarter to	$9$	$:45$

Example: half past three

The minute hand points to $6$ → $30$ minutes past the hour.
The hour hand is between $3$ and $4$, not exactly on $3$.
So we read the time as 3:30 or half past three.

In Question 2, half past three does not make a right angle between the hands. The smaller angle is $75^\circ$, because the hour hand has already moved past $3$.

Triangle Types (by angles)

Acute-angled

All three angles are acute (less than $90^\circ$).

Right-angled

One angle is a right angle ($90^\circ$).

Obtuse-angled

One angle is obtuse (greater than $90^\circ$).

If the greatest angle is acute, the triangle must be an acute-angled triangle.

Key Terms & Definitions (Reference)

Quick glossary for Lesson 1.3 language.

Term	Definition
Cuboid	A rectangular box shape with 6 faces, 8 vertices, 12 edges.
Cube	A special cuboid whose faces are all squares.
Vertex	A corner where edges meet.
Face	A flat side of a solid.
Edge	A line where two faces meet.
Square	Four equal sides and four right angles; a special rectangle.
Acute angle	An angle less than $90^\circ$.
Right angle	An angle equal to $90^\circ$.
Obtuse angle	An angle greater than $90^\circ$ (and less than $180^\circ$).
Acute-angled triangle	All three angles acute.
Right-angled triangle	One right angle.
Obtuse-angled triangle	One obtuse angle.
Kilogram / Gram	Mass units; $1\ \text{kg} = 1000\ \text{g}$.

Key Answers

Quick reference for this lesson’s exercise answers.

1. 8, 6, 12; square, equal; 4 equal sides, 4 right angles, special rectangle; kg, hours, minutes, g; 5 kg, 77 min, 120 s, 458 g; 72

2. ✓, ×, ×

3. A, D, A

4. 7, 169, 630

5–6. 6, 6, 2, 1, 3