Section 1
Rule for Adding Fractions with Like Denominators
Property
To add fractions with like denominators, add the numerators and keep the denominator the same.
This can be represented on a number line as combining lengths from a starting point.
In this Grade 4 lesson from Pengi Math Chapter 7, students learn to add and subtract fractions with like denominators by understanding joining and separating parts of a whole. Using tape diagrams, number bonds, area models, and number lines, they decompose fractions into unit fractions and apply these skills to solve word problems. An extension activity introduces adding fractions with related denominators, such as halves and fourths, by identifying common units.
Section 1
Rule for Adding Fractions with Like Denominators
To add fractions with like denominators, add the numerators and keep the denominator the same.
This can be represented on a number line as combining lengths from a starting point.
Section 2
Rule for Subtracting Fractions with Like Denominators
To subtract fractions with the same denominator, subtract the numerators and keep the denominator the same.
When subtracting fractions that have the same denominator, you only need to perform the subtraction on the numerators. The denominator represents the size of the fractional parts, which remains constant during the operation. This rule is the counterpart to adding fractions with like denominators, where you simply add the numerators.
Section 3
Model Subtracting a Fraction from One on a Number Line
To subtract a fraction from one whole, first rename 1 as a fraction with the same denominator as the fraction being subtracted.
Then, subtract the numerators.
Section 4
Solving Word Problems with Like Fractions
To solve a word problem involving fractions, first identify the given fractions and determine the necessary operation.
Use keywords in the problem to decide whether to add or subtract.
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Section 1
Rule for Adding Fractions with Like Denominators
To add fractions with like denominators, add the numerators and keep the denominator the same.
This can be represented on a number line as combining lengths from a starting point.
Section 2
Rule for Subtracting Fractions with Like Denominators
To subtract fractions with the same denominator, subtract the numerators and keep the denominator the same.
When subtracting fractions that have the same denominator, you only need to perform the subtraction on the numerators. The denominator represents the size of the fractional parts, which remains constant during the operation. This rule is the counterpart to adding fractions with like denominators, where you simply add the numerators.
Section 3
Model Subtracting a Fraction from One on a Number Line
To subtract a fraction from one whole, first rename 1 as a fraction with the same denominator as the fraction being subtracted.
Then, subtract the numerators.
Section 4
Solving Word Problems with Like Fractions
To solve a word problem involving fractions, first identify the given fractions and determine the necessary operation.
Use keywords in the problem to decide whether to add or subtract.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter