Curriculum  /  Math  /  5th Grade  /  Unit 4: Addition and Subtraction of Fractions/Decimals  /  Lesson 14

Addition and Subtraction of Fractions/Decimals

Lesson 14

Math

Unit 4

5th Grade

Lesson 14 of 17

Objective

Add decimals where the total is greater than 2.

Common Core Standards

Core Standards

  • 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

  • 4.NBT.B.4
  • 5.NBT.A.1
  • 4.NF.C.5

Criteria for Success

  1. Understand that in order to add quantities, they must have the same unit (which in the case of decimals, are their place values).
  2. Add like units with decimals using the standard algorithm, aligning places correctly (which results in the decimal points being aligned) (MP.5, MP.6).
  3. Estimate sums of decimals.
  4. Understand that the commutative and associative properties still hold with decimal addition (MP.7).
  5. Solve one-step word problems involving the addition of two decimals (MP.4).

Tips for Teachers

Instead of using language like “aligning the decimal points” when discussing how to set up these computations vertically, instead use language like “aligning like units” or “aligning places” (i.e., ones with ones, tenths with tenths, etc.). Aligning like units results in decimal points being aligned, of course, but it’s because of the need to add and subtract like units that this happens, not the other way around.

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Anchor Tasks

25-30 minutes

Problem 1

a.   Find the value of 1.65 + 0.53.

b.   Mateus used the standard algorithm to add decimals. This is Mateus’s work. Describe what Mateus did in each step.

Step 1:

Step 2:

Step 3:

Guiding Questions

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Student Response

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References

Open Up Resources Grade 5 Unit 5 Lesson 12 — Activity 1

Grade 5 Unit 5 Lesson 12 is made available by Open Up Resources under the CC BY 4.0 license. Copyright © 2017 Open Up Resources. Download for free at openupresources.org. Accessed June 12, 2024, 4:16 p.m..

Modified by Fishtank Learning, Inc.

Problem 2

a.   Estimate the following sums. 

  1. 3.86 + 7.62
  2. 1.39 + 6.7
  3. 1.8 + 24.23
  4. 4.99 + 56.123 + 123.01 + 3.7

b.   Solve for the actual sums in Part (a) above. Are your answers reasonable? Why or why not? 

Guiding Questions

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Student Response

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Problem 3

The decimal points have been erased from the addends on the left-hand side of each equation below. Place a decimal point in each addend to make the equation true. 

a.   3419 + 267 = 60.89

b.   5 + 361 + 47 + 20 = 10.36

Guiding Questions

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Student Response

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Problem Set

15-20 minutes

Discussion of Problem Set

  • Look at #1. When I added, I got 16.00, but I don’t see that as an option. What mistake did I make?
  • Look at #2b. If someone got 64 as an answer, how would you explain to them that their answer is unreasonable?
  • Look at #3. Did anyone solve without actually adding any values together? How were you able to do that?
  • Look at #5. Why does this strategy work? When might it be helpful to use?
  • Who do you agree with in #6? What mistake did the other student make?
  • Look at #7. Who thinks they have the smallest sum? Did anyone get a smaller sum? What was your strategy?

Target Task

5-10 minutes

Solve.

a.   36.25 + 8.67 = __________

b.   4.71 + 23.8 = __________

Student Response

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Additional Practice

The Extra Practice Problems can be used as additional practice for homework, during an intervention block, etc. Daily Word Problems and Fluency Activities are aligned to the content of the unit but not necessarily to the lesson objective, therefore feel free to use them anytime during your school day.

Word Problems and Fluency Activities

Word Problems and Fluency Activities

Help students strengthen their application and fluency skills with daily word problem practice and content-aligned fluency activities.

Next

Subtract decimals where the total is less than or equal to 2.

Lesson 15
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Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: Addition and Subtraction of Fractions

Topic B: Addition and Subtraction of Decimals

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