Chapter 6 · Let's practise geometry

Lesson 6.2 · Perimeter (2)

Hua's Classroom for Shanghai Maths — One Lesson One Exercise (English edition, pages 112–114).

Grade 3 Second Semester Pages 112–114 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. 01Measure and find perimeters of shapes. (Question 1)
  2. 02Reason that the same closed wire has the same perimeter. (Question 2)
  3. 03Explore multi-square block perimeters. (Question 3)

Common Core Standards

CodeStandard (focus for this lesson)
3.MD.D.8Perimeter problems.

Eureka Math Correspondence

Shanghai MathsFocusEureka Math
MeasureRulerG3 M7
WireSame perimeterG3 M7

Core Concepts

Measure sides; same wire → same perimeter for different shapes.

Measure Sides

Measure each side, then add all sides.

Same Wire

A fixed-length closed wire always has the same perimeter, even if the shape changes.

Multi-Square Blocks

Joining squares changes perimeter — overlapping sides are not part of the outer edge.

Key Terms & Definitions (Reference)

Quick glossary for this lesson.

TermDefinition
PerimeterSum of side lengths.
Multi-square blockPolyomino made of unit squares.

Key Answers

Quick reference for this lesson’s exercise answers.

Key answers

  1. Measure (unit mm): measure each side with a ruler, then add. (Depends on print size.)
  2. Grid (1 dm): 20 dm; 18 dm; 22 dm; 22 dm.
  3. MCQ: (1) A; (2) B.
  4. Shapes M & N: same perimeter.
  5. Ant: shortest $7\times8=56$ cm.
  6. Pentominoes: 11 more combinations; shortest perimeter 10 cm.