Unit 1 Parent Guide: Addition and Subtraction with Fractions

Unit 1 Parent Guide: Addition and Subtraction with Fractions

Big Idea 1: Equivalent Fractions

Vocabulary:

Numerator: The top number of a fraction

Denominator: The bottom number of a fraction

Unit Fraction: A fraction with a numerator of 1

Equivalent: Equal - Equivalent fractions are fractions that represent the same part of the whole (ex. ½ and 2/4)

Mixed Number: A number made of a whole number and a fraction

Procedures:

Decomposing a fraction: Break a fraction down into a sum of unit fractions

ex: ¾ = ¼ + ¼ + ¼

Making Equivalent Fractions: Multiply or divide the numerator and denominator of a fraction by the same number. The result is equal to the original fraction, just cut into bigger or smaller pieces.

ex:

Simplifying Fractions: Divide the numerator and denominator by the same number. Do this until no common divisors are left.

ex:

Turning Fractions into Mixed Numbers:

Method 1: Decomposing

7/3 = 3/3 + 3/3 + ⅓ = 1 + 1 + ⅓ = 2 ⅓

Method 2: Dividing

7/3; think 7 ÷ 3 = 2 R 1; so the mixed # is 2 ⅓

The division answer becomes the whole number, the remainder becomes the numerator, and the denominator doesn’t change.

Turning Mixed Numbers into Fractions:

Method 1: Decomposing

2 ½ = 1 + 1 + ½ = 2/2 + 2/2 + ½ = 5/2

Method 2: Multiply then Add

Comparing Fractions:

To compare fractions, first find equivalent fractions with common denominators, then compare the numerators.

Ex:

So ⅗ > ⅓ ; because 9/15 > 5/15

Big Idea 2: Addition and Subtraction with Fractions

Vocabulary:

Sum: Result of an addition problem

Difference: Result of a subtraction problem

Procedures:

Adding and Subtracting fractions:

To add or subtract fractions, you must first find a common denominator. Make equivalent fractions with this common denominator. Once you have a common denominator, add or subtract the numerators and keep the denominator the same.

ex.

Addition: Subtraction:

Adding Mixed Numbers:

Get a common denominator for your fractions. Add the whole numbers, add the numerators, keep the denominator the same. If the resulting fraction is larger than 1, turn it into a mixed number and adjust your answer.

Ex:

Subtracting Mixed Numbers:

Get a common denominator for your fractions. If the bottom fraction is larger than the top fraction, borrow. Subtract the whole numbers, subtract the numerators, and keep the denominator the same.

Ex:

Estimation (Determining if an answer is reasonable):

To estimate a sum or difference, round each fraction to the whole number, then add or subtract. DO NOT solve the problem first and then round your answer.