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Addition of Fractions with Unlike Denominators

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Lesson Plans and Worksheets for Grade 4
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More Lessons for Grade 4
Common Core For Grade 4



Examples, solutions, and videos to help Grade 4 students learn how use visual models to add two fractions with related units using the denominators 2, 3, 4, 5, 6, 8, 10, and 12.

Common Core Standards: 4.NF.3a, 4.NF.3d, 4.NF.1, 4.MD.2

NYS Common Core Grade 4 Module 5, Lesson 21

Grade 4, Module 5, Lesson 21 Worksheets

Lesson 21 Concept Development

Problem 1: Add two fractions with related units modeled with a tape diagram. Use a number bond to rename the sum as a mixed number.
3/8 + 3/4 =

Lesson 21 Problem Set

1. Draw a tape diagram to represent each addend. Decompose one of the tape diagrams to make like units. Then write a complete number sentence. Use a number bond to write each sum as a mixed number.
a. 3/4 + 1/2
b. 2/3 + 3/6
c. 5/6 + 1/3
d. 4/5 + 7/10

2. Draw a number line to model the addition. Then write a complete number sentence. Use a number bond to write each sum as a mixed number.
a. 1/2 + 3/4
b. 1/2 + 6/8
c. 7/10 + 3/5
d. 2/3 + 5/6

3. Solve. Write the sum as a mixed number. Draw a model if needed.
a. 3/4 + 2/8
b. 4/6 + 1/2
c. 4/6 + 2/3
d. 8/10 + 3/5
e. 5/8 + 3/4
f. 5/8 + 2/4
g. 1/2 + 5/8
h. 3/10 + 4/5



Lesson 21 Homework

1. Draw a tape diagram to represent each addend. Decompose one of the tape diagrams to make like units. Then write a complete number sentence. Use a number bond to write each sum as a mixed number.
a. 7/8 + 1/4
b. 4/8 + 2/4
c. 4/6 + 1/2
d. 3/5 + 8/10

2. Draw a number line to model the addition. Then write a complete number sentence. Use a number bond to write each sum as a mixed number.
a. 1/2 + 5/8
b. 3/4 + 3/8
c. 4/10 + 4/5
d. 1/3 + 5/6

3. Solve. Write the sum as a mixed number. Draw a model if needed.
a. 1/2 + 6/6
b. 7/8 + 3/4
c. 5/6 + 1/3
d. 9/10 + 2/5
e. 4/12 + 3/4
f. 1/2 + 5/6
g. 3/12 + 5/6
h. 7/10 + 4/5


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