Steps- Fraction Model
What is the first step when solving adding and subtracting fractions with unlike denominators?
Model one each fraction on a different one whole block or .
2 1
____ + ____ =
3 4
11
___
12
What is a denominator?
The number below the line in a fraction.
What is the second step when adding and subtracting fractions with unlike denominators?
Create equivalent fractions with like denominators.
3 2
____ + ___ =
4 3
17 /12 or 1 5/12
What is a numerator?
The number above the line in a fraction.
What is the third step when adding and subtracting fractions with unlike denominators?
Add fractions with like denominators.
4 3
____ + ___ =
5 4
31/20 or 1 11/20
What does equivalent mean?
Equal in value or the same in value.
What is the fourth step when adding and subtracting fractions with unlike denominators?
Simplify the fraction (If Needed).
6 5
____ + ___ =
7 6
71
_____
42
What does simplify mean?
To reduce a fraction to it's simplest form.
How can we check that our answer is reasonable?
We can compare the fractions to the fraction 1/2 if it is less than 1 or compare the fractions to a whole number if larger than 1.
Mr. Kreider wants to paint two doors and several shutters. It takes 2 1/8 gallons of paint to coat each door and 1 3/5 gallons of paint to coat all of his shutters. If Mr. Kreider buys three 2-gallon cans of paint, does he have enough to complete the job?
Yes, because he will have 6 gallons in all and we have less than 6 being used.
What is a common denominator?
When your denominators are the same value.