Learn on PengiPengi Math (Grade 4)Chapter 2: Algorithms, Fluency, and Multi-Step Problem Solving

Lesson 4: Modeling Addition, Subtraction, and Comparison with Tape Diagrams

In this Grade 4 Pengi Math lesson from Chapter 2, students learn to solve addition, subtraction, and additive comparison word problems using the Read-Draw-Write (RDW) process. They use tape diagrams to model part-whole relationships and interpret comparison situations, such as finding a difference or calculating a total when a difference is known.

Section 1

Solving Addition Word Problems Using Tape Diagrams

Property

A tape diagram models an addition problem by representing the addends as parts of a whole. The total, or sum, is the unknown whole. This relationship can be shown with the equation: $Part + Part = Whole$ .

Examples

Section 2

Modeling Subtraction with Tape Diagrams

Property

A tape diagram for subtraction illustrates the relationship $Whole = Part + Part$ . In a subtraction problem, the total amount is the $Whole$ , and the number being subtracted is a known $Part$ . The goal is to find the unknown $Part$ , which is the difference:

Whole - Part_{known} = Part_{unknown}

Examples

Section 3

Modeling Additive Comparisons with Tape Diagrams

Property

To find the difference ( $D$ ) between a larger quantity ( $L$ ) and a smaller quantity ( $S$ ) in an additive comparison problem, you subtract the smaller quantity from the larger quantity.

L - S = D

Examples

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

Solving Addition Word Problems Using Tape Diagrams

Property

Examples

Section 2

Modeling Subtraction with Tape Diagrams

Property

Whole - Part_{known} = Part_{unknown}

Examples

Section 3

Modeling Additive Comparisons with Tape Diagrams

Property

To find the difference ( $D$ ) between a larger quantity ( $L$ ) and a smaller quantity ( $S$ ) in an additive comparison problem, you subtract the smaller quantity from the larger quantity.

L - S = D

Examples

Overview

Lesson overview

Review the lesson summary and core properties without leaving the current page.

Overview

Section 1

Solving Addition Word Problems Using Tape Diagrams

Property

Examples

Section 2

Modeling Subtraction with Tape Diagrams

Property

Whole - Part_{known} = Part_{unknown}

Examples

Section 3

Modeling Additive Comparisons with Tape Diagrams

Property

To find the difference ( $D$ ) between a larger quantity ( $L$ ) and a smaller quantity ( $S$ ) in an additive comparison problem, you subtract the smaller quantity from the larger quantity.

L - S = D