Go Math Lesson 6.4

Go Math-Chapter 6 (Add and Subtract Fractions)

5th Grade

Addition with Unlike Denominators

• Find the least common denominator (LCD). This is the smallest number that both denominators can fit into.

• Create equivalent fractions if needed.

• Add

Multiple Choice

$$\frac{3}{5}+\frac{1}{2}=$$  

Simplify

• $$\frac{4}{7}$$  

• $$1\ \frac{1}{10}$$  

Multiple Choice

$$\frac{2}{3}+\frac{1}{6}=$$  


Simplify

• $$\frac{5}{6}$$  

• $$\frac{3}{6}$$  

• $$\frac{3}{9}$$  

Subtraction with Unlike Denominators

• Find the least common denominator (LCD). This is the smallest number that both denominators can fit into.

• Create equivalent fractions if needed.

• Subtract

Multiple Choice

$$\frac{3}{5}-\frac{3}{10}=$$  

• $$\frac{0}{15}$$  

• $$\frac{3}{10}$$  

Multiple Choice

$$\frac{5}{8}-\frac{1}{2}=$$  

• $$\frac{4}{6}$$  

• $$\frac{6}{10}$$  

• $$\frac{1}{8}$$  

Common Denominators and Equivalent Fractions

• Strategy 1: Multiply the Denominators

• Strategy 2: Use a list, Multiples (count by each denominator and find the number they both hit)

Multiple Select

Select ALL of the fractions equivalent to

$$\frac{2}{3}$$  
(Hint: There are 3 correct options)

• $$\frac{4}{6}$$  

• $$\frac{3}{4}$$  

• $$\frac{6}{9}$$  

• $$\frac{8}{12}$$  

Multiple Choice

Are the following fractions equivalent?

$$\frac{5}{6}\ and\frac{15}{18}$$  

• Yes

• No

Add and Subtract Mixed Numbers

• If there unlike denominators, find the LCD and change fractions so that they have common denominators

• Add or Subtract

Multiple Choice

$$1\ \frac{2}{5}+2\ \frac{1}{10}=$$  

Reduce

• $$3\ \frac{3}{15}$$  

• $$3\ \frac{1}{2}$$  

• $$3\ \frac{3}{10}$$  

Multiple Choice

$$4\ \frac{5}{6}-2\ \frac{3}{4}=$$  

• $$2\ \frac{8}{10}$$  

• $$2\ \frac{2}{12}$$  

• $$2\ \frac{1}{12}$$  

• 2

Multiple Choice

$$5\ \frac{3}{4}+\ 1\frac{1}{3}=$$  

• $$6\ \frac{4}{7}$$  

• 4

• $$7\ \frac{1}{12}$$  

Subtraction with Renaming

• Rewrite the fractions with common denominators

• Borrow from the first whole number by rewriting it as a whole number + one written as a fraction

• Add the fraction equal to one to the other fraction

• Subtract the whole numbers

• Subtract the fractions

• Simplify if needed

Multiple Choice

$$2\ \frac{1}{2}-1\ \frac{5}{6}=$$  

Subtract and simplify

• $$1\ \frac{4}{4}$$  

• $$1\ \frac{5}{6}$$  

• $$\frac{2}{3}$$  

Multiple Choice

$$9\ \frac{1}{6}-2\ \frac{3}{4}=$$  

Subtract and simplify

• $$6\ \frac{5}{12}$$  

• 7

• $$7\ \frac{1}{2}$$  

Multiple Choice

$$13\ \frac{1}{6}-3\ \frac{4}{5}=$$  

Subtract and simplify

• $$10\ \frac{5}{11}$$  

• 10

• $$9\ \frac{11}{30}$$  

Problem Solving (Word Problems)

• What do you need to find out?

• What do you already know?

• Which operation or operations do you need to do?

• Label

Multiple Choice

Thelma spent 1/6 of her weekly allowance on dog toys, 1/4 on a dog collar, and 1/3 on dog food. What fraction of her weekly allowance is left?

• $$\frac{1}{4}$$ of her allowance

• $$\frac{3}{13}$$ of her allowance
  

• $$\frac{5}{6}$$ of her allowance

Multiple Choice

Della bought a tree seedling that was 2 1/4 feet tall. During the first year, it grew 1 1/6 feet. After two years, it was 5 feet tall. How much did the seedling grow during the second year?

• $$7\ \frac{5}{6}$$ feet

• 32 feet

• $$1\ \frac{7}{12}$$ feet

• 2 feet

Multiple Choice

Marcie bought a 50-foot roll of packing tape. She used two 8 5/6 -foot lengths. How much tape is left on the roll?

• $$32\ \frac{1}{3}$$ feet of tape

• 33 feet of tape

• $$33\ \frac{1}{3}$$ feet of tape

Properties of Addition

• Use the Associative Property to put fractions with like denominators next to each other

• Use the Commutative Property to put fractions with like denominators in a group using parentheses ( )

• Add

• Simplify if needed

Multiple Choice

$$\left(2\ \frac{5}{8}+1\ \frac{2}{3}\right)+1\ \frac{1}{8}=$$  

Add

• 4

• $$\frac{77}{12}$$  

• $$4\ \frac{8}{19}$$  

• $$5\ \frac{5}{12}$$  

Multiple Choice

$$\left(\frac{2}{7}+\frac{1}{3}\right)+\frac{2}{3}=$$  
Add

• $$1\ \frac{2}{7}$$  

• $$\frac{5}{13}$$  

• 3