Adding & Subtracting Fractions
Find a common denominator for 3/4 and 1/3
Possible Answers: 12, 24
What is 1/8 of 72?
9
Solve using the standard multiplication algorithm:
2/5 x 3/8
6/40 or 3/20
Marcus ran 3 5/6 miles on Saturday and 2 1/6 miles on Sunday. What is the total distance he ran this weekend?
7 miles
Create a real-world word story that matches the expression:
1/5 (divided by) 4
Add.
2/3 + 1/5
13/15
32 x 3/8
Solve using the standard multiplication algorithm:
3/4 x 5/7
15/28
Write a division number model for this situation and draw a model.
1/3 gallon of orange juice is poured equally into 5 glasses
1/3 (divided by) 5 = 1/15
Teacher will check your model.
Find the least common denominator for this set of fractions:
1/3 and 1/4 and 1/5
Show your list of multiples to prove your answer.
3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 42, 45, 48, 51, 54, 57, 60
4, 8 ,12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60
5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60
Least Common Denominator= 60
Explain the strategy for finding a common denominator for the numbers 6 and 4. Why do we need a common denominator to add or subtract fractions?
You can use the Quick Common Denominator (QCD) by multiplying the two denominators you are given, or you can list the multiples of both denominators and use a number that appears in both lists. We need common denominators to add and subtract fractions because we need to be working with the same-sized pieces.
Find 4/5 of 25
Answer: 20
Create an area model to represent 3/5 of 2/3.
Shade the final product clearly.
Write the multiplication sentence you would use to check the follwing problem:
6 (divided by) 1/4 = 24
24 x 1/4= 24/4= 6
Solve the following multi-step problem. Show each step of your work:
2 x 3/4 - 1/2 (divided by) 2
6/4 - 1/4= 5/4 or 1 1/4
Estimate & then solve:
3 1/4 + 2 2/5
5 13/20
Without solving, explain if 24 x 5/4 is greater than or less than 24? How does the fraction affect the size of the product?
The answer will be greater than 24 because you are multiplying by 5/4, which is an improper fraction which means it is greater than 1. When you multiply by a fraction greater than 1 your answer will get bigger.
Use an area model to solve this problem. What is the final product?
1/3 x 1/6
1/18
Teacher will check your model
Solve this problem using a model and provide a number sentence: You have 4 pounds of colorful sand. If you put the sand into small bags that hold 1/4 pound each, how many bags can you fill?
16 bags
4 (divided by) 1/4= 16
Create an area model for:
2/3 x 3/4
Write the final product in simplest form.
6/12
Simplest form: 1/2
Estimate, then solve
5/6 - 1/4
Possible Answers:
13/12 or 1 1/12
26/24 or 1 2/24
Write your own number story for 18 x 2/9. Solve it.
Answer: 4
Number Stories will vary.
Draw a model to show why 4/5 x 1/2 = 4/10
After your draw your model, make sure you have labeled it with fractional parts and write an explanation that details what you did.
Teacher will check your model and explanation.
Write your own DIVISION NUMBER STORY for the following:
1/2 (divided by) 14
Number stories will vary. Teacher will check your number story.
A recipe calls for 3/4 cup of sugar. If you want to make half of the recipe, you can either divide by 2 or multiply by 1/2
Prove that both methods result in the same amount of sugar using math and a written explanation.
Teacher will check your work and listen to your explanation