Addition and Subtraction of Fractions/Decimals
Lesson 13
Objective
Add decimals.
Common Core Standards
Core Standards
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5.NBT.B.7 — Add, subtract, multiply, and divide decimals to hundredths, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.
Foundational Standards
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5.NBT.A.1
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5.NBT.A.4
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4.NF.C.5
Criteria for Success
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- Understand that in order to add quantities, they must have the same unit (which in the case of decimals, are their place values).
- Add like units with decimals using an area model or the standard algorithm, aligning place values correctly (which results in the decimal points being aligned) (MP.5, MP.6).
- Estimate sums of decimals.
- Understand that the commutative and associative properties still hold with decimal addition (MP.7).
- Solve one-step word problems involving the addition of two decimals (MP.4).
Tips for Teachers
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As a supplement to the Problem Set, students can solve the puzzle "Decimal Addition Puzzle" from 5.NBT.7 - About the Math, Learning Tasks, and Rigor by the Howard County Public School System.
Remote Learning Guidance
If you need to adapt or shorten this lesson for remote learning, we suggest prioritizing Anchor Tasks 2 and 4 (benefit from worked examples). Find more guidance on adapting our math curriculum for remote learning here.
Anchor Tasks
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Problem 1
- Solve.
- 3 eighths + 1 fourth = ___________
- 3 fifths + 1 half = ___________
- 3 tenths + 1 hundredth = ___________
- What do you notice about #1 above? What do you wonder?
Guiding Questions
Problem 2
Solve. Show your work with an area model.
a. 0.3 + 0.5
b. 0.64 + 0.7
Guiding Questions
Problem 3
Solve. Show your work.
a. 3.37 + 10.64
b. 0.7 + 15
Guiding Questions
Problem 4
- Estimate the following sums.
- 3.419 + 2.67
- 4.99 + 56.123 +123.01 + 3.7
- Solve for the actual sums in #1 above. Are your answers reasonable? Why or why not?
Guiding Questions
Problem Set & Homework
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- Problem Set Answer Key
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- Homework Answer Key
Discussion of Problem Set
- Look at #2d. If someone got 64 as an answer, how would you explain to them that their answer is unreasonable?
- Look at #3. Is Jeremy’s answer reasonable? How do you know? What mistake did he make?
- Look at #4. Did anyone solve without actually adding any values together? How were you able to do that?
- Look at #5. When I added, I got 16.00, but I don’t see that as an option. What mistake did I make?
- Look at #7. Why does this strategy work? When might it be helpful to use?
- Look at #8. Who thinks they have the smallest sum? Did anyone get a smaller sum? What was your strategy?
Target Task
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Solve.
1. 2.40 + 1.8 = __________
2. 36.25 + 8.67 = __________
References
Grade 5 Mathematics > Module 1 > Topic D > Lesson 9 of the New York State Common Core Mathematics Curriculum from EngageNY and Great Minds. © 2015 Great Minds. Licensed by EngageNY of the New York State Education Department under the CC BY-NC-SA 3.0 US license. Accessed Dec. 2, 2016, 5:15 p.m..
Modified by Fishtank Learning, Inc.Mastery Response
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Additional Practice
Unit Practice
With Fishtank Plus you can access our Daily Word Problem Practice and our content-aligned Fluency Activities created to help students strengthen their application and fluency skills.
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