You Tube Shorts
GED MATH for Adults: Adding Fractions
Overview
Designed for use in the adult education classroom to present an alternative method for adding fractions with different denominators than most are accustomed to.
Learning Objectives
- introduce the butterfly method to add fractions with different denominators
- "draw" the butterfly
- accurately add fractions with different denominators using the butterfly method
- understand when NOT to utilize the butterfly method when adding fractions
Introduction
Remember back in school when you were learning to add fractions?
More than likely you were taught to find a least common denominator (LCD)
Here, we will use another method to quickly add fractions using what is known as the butterfly method.
Let's check it out ... click the attached link to view on YouTube for a quick preview
STEP BY STEP ...
We will encircle the first diagonal of 2 and 4. MULTIPLY them together (yes, multiply!) and write the total above the circle.
2 x 4 = 8
Do the same with the next diagonal of 3 and 5. Multiply them together and write the total above the circle.
3 x 5 = 15
Then, encircle the denominators (bottom of the fraction). Multiply them together and write the total BELOW the circle.
5 x 4 = 20
I like to place the + sign on the top as a reminder that I can now ADD the totals at the top (numerator)
8 + 15 = 23
So...... we have the fraction 23/20
If needed, we can convert this improper fraction (numerator larger than denominator) to a mixed number
Let's watch this in action again
Guided Practice
Use this guided practice to accurately add the fractions using the butterfly method.
ANSWER KEY to GUIDED PRACTICE
11/10 or 1 1/10 11/12 13/20
Now YOU try ...
Add the following fractions:
ANSWER KEY to Now YOU try...
The correct answers are:
#1 17/12 or 1 5/12 #2 39/120 or 13/40 #3 21/18 or 1 1/6
When NOT to use this method ... THINK!!!
Remember least common denominators?
We use these to add fractions that have DIFFERENT denominators.
THINK!!!
If the denominators are ALREADY THE SAME, just ADD the numerators and KEEP the SAME denominator. NO need to use the butterfly method.
EXAMPLE:
1/3 + 1/3 = 2/3 (just add the numerators)
4/25 + 20/25 = 24/25
VOILA!!!
What's next?
- We will use the butterfly method to SUBTRACT fractions!
- We will use the two diagonals of the butterfly method to COMPARE fractions!