Mixed Number Mania: Adding and Subtracting Fractions with Different Denominators

Mathematics Grades 5th Grade 5:25 Video
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Lesson Description

Learn how to confidently add and subtract mixed numbers with unlike denominators. This lesson uses Mr. J's video to guide you through finding common denominators, renaming fractions, and simplifying your final answers.

Video Resource

Adding and Subtracting Mixed Numbers with Unlike Denominators | Math with Mr. J

Math with Mr. J

Duration: 5:25
Watch on YouTube

Key Concepts

  • Mixed Numbers
  • Unlike Denominators
  • Least Common Denominator (LCD)
  • Renaming Fractions
  • Simplifying Fractions

Learning Objectives

  • Students will be able to find the least common denominator of two or more fractions.
  • Students will be able to rename fractions to have a common denominator.
  • Students will be able to add and subtract mixed numbers with unlike denominators.
  • Students will be able to simplify fractions in their final answer.

Educator Instructions

  • Introduction (5 mins)
    Begin by reviewing what mixed numbers and denominators are. Ask students to share examples of mixed numbers they might see in everyday life (e.g., cooking measurements). Briefly discuss why fractions need a common denominator before they can be added or subtracted.
  • Video Viewing (10 mins)
    Play the 'Adding and Subtracting Mixed Numbers with Unlike Denominators | Math with Mr. J' video. Encourage students to take notes on the steps Mr. J outlines for solving these problems. Pause the video at key points to allow for questions and clarification.
  • Guided Practice (15 mins)
    Work through example problems similar to those in the video on the board. Verbalize each step clearly, explaining why you are finding the LCD, renaming the fractions, and then adding/subtracting. Include both addition and subtraction examples.
  • Independent Practice (15 mins)
    Provide students with a worksheet containing problems involving adding and subtracting mixed numbers with unlike denominators. Have students work independently or in pairs to solve the problems. Circulate to provide support and answer questions.
  • Review and Wrap-up (5 mins)
    Review the answers to the independent practice problems. Address any remaining questions or misconceptions. Summarize the key steps for adding and subtracting mixed numbers with unlike denominators.

Interactive Exercises

  • Fraction Match Game
    Create a matching game where students match fractions with unlike denominators to their equivalent fractions with a common denominator.
  • Online Fraction Practice
    Use a website or app that provides interactive practice with adding and subtracting fractions. (e.g., Khan Academy, Math Playground).

Discussion Questions

  • Why is it important to have a common denominator when adding or subtracting fractions?
  • What is the easiest way to find the least common denominator?
  • How do you know when a fraction is in simplest form?
  • Can you think of a real-world situation where you might need to add or subtract mixed numbers?

Skills Developed

  • Problem-solving
  • Critical Thinking
  • Fraction Manipulation
  • Attention to Detail

Multiple Choice Questions

Question 1:

What is the first step when adding mixed numbers with different denominators?

Correct Answer: Find a common denominator.

Question 2:

What is the least common denominator (LCD) of 1/3 and 1/4?

Correct Answer: 12

Question 3:

2 1/2 + 1 1/4 = ?

Correct Answer: 3 3/4

Question 4:

5 2/3 - 2 1/3 = ?

Correct Answer: 3 1/3

Question 5:

To simplify a fraction, you need to:

Correct Answer: Divide the numerator and denominator by a common factor.

Question 6:

What is 6/8 simplified?

Correct Answer: 3/4

Question 7:

When subtracting mixed numbers, if the second fraction is bigger than the first, you might need to:

Correct Answer: Borrow from the whole number.

Question 8:

The common denominator of 1/5 and 1/2 is:

Correct Answer: 10

Question 9:

What is 3 1/4 + 2 2/4?

Correct Answer: 5 3/4

Question 10:

What is 7 5/8 - 4 1/8?

Correct Answer: 3 4/8

Fill in the Blank Questions

Question 1:

A number with a whole number and a fraction is called a _____ _____.

Correct Answer: mixed number

Question 2:

The bottom number in a fraction is called the _________.

Correct Answer: denominator

Question 3:

The top number in a fraction is called the _________.

Correct Answer: numerator

Question 4:

The smallest common multiple of two or more denominators is called the _____ ________ ___________.

Correct Answer: least common denominator

Question 5:

Fractions that have the same value, but look different, are called __________ fractions.

Correct Answer: equivalent

Question 6:

To make a fraction simpler, you should find a _____ _____ between the top and bottom number.

Correct Answer: common factor

Question 7:

When adding or subtracting fractions, you must first have a __________ __________.

Correct Answer: common denominator

Question 8:

4/12 simplified is __________.

Correct Answer: 1/3

Question 9:

To find an equivalent fraction, do the same thing to the ______ and denominator.

Correct Answer: numerator

Question 10:

When adding mixed numbers, add the fractions and the _________ __________ separately.

Correct Answer: whole numbers

Educational Standards

5.N.3:[Standard] Add and subtract fractions with like and unlike denominators, mixed numbers, and decimals to solve real-world and mathematical problems. 5.N.3.3:[Objective] Add and subtract fractions with like and unlike denominators, mixed numbers, and decimals, involving money, measurement, geometry, and data. Use various models and efficient strategies, including but not limited to standard algorithms. 5.N.3.1:[Objective] Estimate sums and differences of fractions with like and unlike denominators, mixed numbers, and decimals to assess the reasonableness of the results.

Teaching Materials

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