Fraction Action: Subtracting Fractions with Unlike Denominators
Lesson Description
Video Resource
Subtracting Fractions with Unlike Denominators | Math with Mr. J
Math with Mr. J
Key Concepts
- Unlike Denominators
- Least Common Multiple (LCM)
- Equivalent Fractions
- Renaming Fractions
- Simplifying Fractions
Learning Objectives
- Students will be able to find the least common multiple (LCM) of two or more denominators.
- Students will be able to rename fractions with unlike denominators to equivalent fractions with a common denominator.
- Students will be able to subtract fractions with unlike denominators.
- Students will be able to simplify fractions after subtraction.
Educator Instructions
- Introduction (5 mins)
Begin by reviewing what fractions are and the parts of a fraction (numerator and denominator). Ask students what they already know about adding and subtracting fractions with the same denominators. Then, introduce the problem of subtracting fractions with different denominators and explain that they will learn how to solve these types of problems in the video. - Video Viewing (10 mins)
Play the "Subtracting Fractions with Unlike Denominators | Math with Mr. J" video. Encourage students to take notes on the steps Mr. J explains. Pause the video at the example problems to give students a chance to try solving them on their own before Mr. J reveals the solution. - Guided Practice (15 mins)
Work through a few subtraction problems with unlike denominators as a class. Follow the steps outlined in the video: 1) Find the LCM of the denominators, 2) Rename the fractions with the common denominator, 3) Subtract the numerators, and 4) Simplify the resulting fraction if possible. Emphasize the importance of showing all work. - Independent Practice (15 mins)
Provide students with a worksheet containing various subtraction problems with unlike denominators. Have them work individually to solve the problems, showing all their steps. Circulate the room to provide assistance and answer questions. - Review and Wrap-up (5 mins)
Review the key steps for subtracting fractions with unlike denominators. Ask students if they have any remaining questions. Collect the worksheets for assessment. Briefly discuss real-world scenarios where subtracting fractions might be useful (e.g., sharing a pizza, measuring ingredients for a recipe).
Interactive Exercises
- Fraction Frenzy Game
Divide the class into teams. Write subtraction problems with unlike denominators on the board. One member from each team races to the board to solve a problem correctly. The first team to solve the problem correctly earns a point. The team with the most points at the end of the game wins! - Online Fraction Subtraction Practice
Use online resources like Khan Academy or Math Playground for interactive practice on subtracting fractions with unlike denominators. Have students complete a set number of problems and track their progress.
Discussion Questions
- Why do we need a common denominator when subtracting fractions?
- What is the least common multiple (LCM) and why is it important when subtracting fractions with unlike denominators?
- How do you rename a fraction to an equivalent fraction with a different denominator?
- What does it mean to simplify a fraction, and why is it important?
Skills Developed
- Problem-solving
- Critical thinking
- Mathematical reasoning
- Procedural fluency
- Simplifying fractions
Multiple Choice Questions
Question 1:
What do you need to subtract fractions with different denominators?
Correct Answer: A common denominator
Question 2:
What is the first step when subtracting fractions with unlike denominators?
Correct Answer: Find the least common multiple
Question 3:
What is the least common multiple (LCM)?
Correct Answer: The smallest multiple of two numbers
Question 4:
What does it mean to rename a fraction?
Correct Answer: To find an equivalent fraction with a different denominator
Question 5:
What do you do with the denominators after you find a common denominator and rename the fractions?
Correct Answer: Keep them the same
Question 6:
What is 1/2 renamed with a denominator of 6?
Correct Answer: 3/6
Question 7:
What is 2/3 renamed with a denominator of 9?
Correct Answer: 6/9
Question 8:
What is 5/10 simplified?
Correct Answer: 1/2
Question 9:
Which fraction is equivalent to 2/4?
Correct Answer: 1/2
Question 10:
After subtracting fractions, what should you always check to see if you can do?
Correct Answer: Divide
Fill in the Blank Questions
Question 1:
The top number of a fraction is called the ______.
Correct Answer: numerator
Question 2:
The bottom number of a fraction is called the ______.
Correct Answer: denominator
Question 3:
When subtracting fractions with different denominators, you need to find a ______ denominator.
Correct Answer: common
Question 4:
The smallest multiple that two numbers share is called the ______ ______ ______ (LCM).
Correct Answer: least common multiple
Question 5:
Changing a fraction to an equivalent fraction with a different denominator is called ______ the fraction.
Correct Answer: renaming
Question 6:
Fractions that have the same value, but look different, are called ______ fractions.
Correct Answer: equivalent
Question 7:
After subtracting the numerators, you keep the ______ the same.
Correct Answer: denominator
Question 8:
Dividing the numerator and denominator by the same number is a way to ______ a fraction.
Correct Answer: simplify
Question 9:
2/4 and 1/2 are ______ fractions.
Correct Answer: equivalent
Question 10:
The LCM of 4 and 6 is ______.
Correct Answer: 12
Educational Standards
Teaching Materials
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