Fraction Frenzy: Adding Fractions with Unlike Denominators

Mathematics Grades 7th Grade 4:02 Video
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Lesson Description

Learn how to add fractions with different denominators by finding a common denominator. This lesson uses visual aids and examples to make the process clear and easy to understand.

Video Resource

Adding fractions with unlike denominators introduction

Khan Academy

Duration: 4:02
Watch on YouTube

Key Concepts

  • Unlike Denominators
  • Common Denominator
  • Equivalent Fractions
  • Least Common Multiple (LCM)

Learning Objectives

  • Students will be able to identify fractions with unlike denominators.
  • Students will be able to find a common denominator for two or more fractions.
  • Students will be able to rewrite fractions as equivalent fractions with a common denominator.
  • Students will be able to add fractions with unlike denominators.

Educator Instructions

  • Introduction (5 mins)
    Begin by reviewing what a fraction represents and the concept of the numerator and denominator. Introduce the problem of adding fractions with unlike denominators, emphasizing why it's different from adding fractions with like denominators.
  • Video Presentation (7 mins)
    Play the Khan Academy video 'Adding fractions with unlike denominators introduction'. Encourage students to pay attention to the visual representations and the explanation of finding a common denominator. Pause at key points to clarify any confusion.
  • Guided Practice (10 mins)
    Work through a few example problems on the board, guiding students through the steps of finding the least common multiple (LCM) of the denominators, rewriting the fractions with the common denominator, and then adding the numerators. Use visual aids like fraction bars or circles to further illustrate the concept.
  • Independent Practice (10 mins)
    Provide students with a set of practice problems to work on individually. Circulate the classroom to provide assistance as needed. Encourage students to check their answers and work together to solve any problems they are struggling with.
  • Wrap-up (3 mins)
    Summarize the key steps for adding fractions with unlike denominators. Answer any remaining questions. Preview the next lesson, which could involve more complex fractions or subtracting fractions with unlike denominators.

Interactive Exercises

  • Fraction Bars Activity
    Provide students with physical or digital fraction bars. Have them represent the fractions being added, find a common denominator by dividing the bars into smaller equal sections, and then physically combine the bars to find the sum.
  • Online Fraction Games
    Direct students to online games or interactive websites that provide practice in adding fractions with unlike denominators. These games can make the process more engaging and provide immediate feedback.

Discussion Questions

  • Why can't we directly add fractions with different denominators?
  • What is a common denominator, and why is it important?
  • How does finding the least common multiple (LCM) help us add fractions?
  • Can you think of real-world examples where you might need to add fractions with unlike denominators?

Skills Developed

  • Finding Least Common Multiples
  • Creating Equivalent Fractions
  • Problem-Solving
  • Visual Representation of Fractions

Multiple Choice Questions

Question 1:

What must you find before you can add two fractions with unlike denominators?

Correct Answer: A common denominator

Question 2:

What is the least common multiple (LCM) of 4 and 6?

Correct Answer: 12

Question 3:

What is 1/2 + 1/4?

Correct Answer: 3/4

Question 4:

What is the equivalent fraction of 2/3 with a denominator of 9?

Correct Answer: 6/9

Question 5:

To add 1/5 + 1/2, what common denominator could you use?

Correct Answer: 10

Question 6:

What is 3/8 + 1/4?

Correct Answer: 5/8

Question 7:

Why is it important to have a common denominator when adding fractions?

Correct Answer: To compare the sizes of the fractions easily

Question 8:

Which of the following is an equivalent fraction for 1/3?

Correct Answer: 2/6

Question 9:

To convert 1/3 to an equivalent fraction with a denominator of 12, what do you multiply the numerator and denominator by?

Correct Answer: 6

Question 10:

What is 2/5 + 1/10?

Correct Answer: 5/10

Fill in the Blank Questions

Question 1:

Before adding fractions with different denominators, you need to find a _______ __________.

Correct Answer: common denominator

Question 2:

The least common multiple of 3 and 5 is ______.

Correct Answer: 15

Question 3:

1/4 is equivalent to _____/8.

Correct Answer: 2

Question 4:

To add 1/3 + 1/6, you can rewrite 1/3 as _____/6.

Correct Answer: 2

Question 5:

The sum of 1/2 and 1/5 is _____/10.

Correct Answer: 7

Question 6:

To find a common denominator, look for a common __________ of the original denominators.

Correct Answer: multiple

Question 7:

2/3 + 1/6 = _____/6

Correct Answer: 5

Question 8:

When adding fractions, you only add the __________.

Correct Answer: numerators

Question 9:

If the denominator of a fraction is 4 and you want to make the denominator 12, you need to multiply by __________.

Correct Answer: 3

Question 10:

Adding 3/10 + 2/5 results in a sum of _____/10.

Correct Answer: 7

Educational Standards

7.N.1:[Standard] Read, write, represent, and compare rational numbers, expressed as integers, fractions, and decimals. Explain and apply the concept of absolute value. 7.N.1.2:[Objective] Recognize and generate equivalent representations of rational numbers, including equivalent fractions. 7.N.2.5:[Objective] Model and solve problems using rational numbers involving addition, subtraction, multiplication, division, and positive integer exponents.

Teaching Materials

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