Lesson Standard: 5.NF.2 Solve word problems involving addition and subtraction of fractions referring to the same whole, including cases with unlike denominators, e.g., by using visual fraction models or equations to represent the problems. Use benchmark fractions and number sense of fractions to estimate mentally and assess the reasonableness of answers.
Content Objective: Students will use benchmark fractions and number sense of fractions to estimate mentally and assess the reasonableness of answers.
Mathematical practice(s): 1 Make sense of problems and persevere, 4 Model with mathematics, 6 Attend to precision
Lesson Design / What will the teacher be doing? / What will the students be doing?(Structured Student Interaction) / What will the teacher be listening for?
(What do we expect students to say?) / Probing Questions for Differentiation
Assessing Questions
(“stuck”) / Advancing Questions
(further learning)
Engage (Launch)
4/8, 7/14, 6/12, 5/10 What do you notice about these fractions? What do you wonder about these fractions?
How do you know it is one half?
Give numerator students respond with denominator. (Students can show on their fingers)2, 4, 5 numerators
Give denominator, students respond with numerator. (Students can show on their fingers)12th , 20th , 100th denominators
If the denominator is 7 what is the numerator?
What would be a way to write one whole as a fraction? What is the relationship between the numerator and denominator?
How many halves are equal to zero? What is the relationship between the numerator and denominator? / Teacher will place the fractions on the board and ask students to discuss the questions with their partner.
After questions …. State: now we know some benchmark numbers. 0, ½, 1. (Draw a number line on the board and place the benchmarks on the number line) These numbers help us when we are discussing fractions. Benchmarks are numbers we know for sure and can compare fractions against them. / Students will discuss their answer with their partner. Partner A will share first. / Equal to ½
Numerator
Denominator
Numerator is ½ of the denominator / Do you see any relationship between the numerator and denominator? / Add fractions with the same relationship to the list.
Activity or Task 1
Kimberly is riding her bike to school. The distance from her house to school is 7/8 of a mile. About how far is Kimberly’s house from the school? Show how you know. / Teacher will place problem on doc camera and have students work with a partner to discuss the answer. / Students will work with partner to answer the problem. Students will show on their whiteboards how they know their answer is right. (Bs are writing) / Number lines
Use of benchmark numbers / Can you relate it to a benchmark number? / How do you know it isn’t closer to 1/2?
Activity or Task 2
Kimberly is now in middle school. The distance to her middle school is 3/5 of a mile more. About how far did she ride altogether? / Teacher will place problem on doc camera and have students work with a partner to discuss the answer. / Students will work with partner to answer the problem. Students will show on their whiteboards how they know their answer is right. (As write) / Number lines
Use of benchmark numbers / Can you relate it to a benchmark number?
Activity or Task 3
Kimberly will be riding her bike to the store. The distance from her house to the end of the street is 1/6 of a mile. The distance from the end of the street to the store is 3/8 of a mile. About how far is Kimberly’s house from the store? / Teacher will place problem on doc camera and have students work with a partner to discuss the answer. / Students will work with partner to answer the problem. Students will show on their whiteboards how they know their answer is right. (As write) / Number lines
Use of benchmark numbers / Can you relate it to a benchmark number?
Closure
Estimate the sum or difference.
9/10 – 5/8
4 2/7 – 2 3/5 / Hand out the papers for students complete independently. / Students complete handout independently.
Kimberly is riding her bike to school. The distance from her house to school is 7/8 of a mile. About how far is Kimberly’s house from the school? Show how you know.
Now Kimberly is going to middle school. The distance to her middle school is 3/5 of a mile more. About how far did she ride altogether?
Kimberly will be riding her bike to the store. The distance from her house to the end of the street is 1/6 of a mile. The distance from the end of the street to the store is 3/8 of a mile. About how far is Kimberly’s house from the store?
- Estimate the sum or difference using benchmarks. Show your thinking.
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- Estimate the sum or difference using benchmarks. Show your thinking.
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