# Decimal Fractions

## Objective

Solve word problems involving the addition of decimals and decimal fractions.

## Common Core Standards

### Core Standards

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• 4.NF.C.5 — Express a fraction with denominator 10 as an equivalent fraction with denominator 100, and use this technique to add two fractions with respective denominators 10 and 100. Students who can generate equivalent fractions can develop strategies for adding fractions with unlike denominators in general. But addition and subtraction with unlike denominators in general is not a requirement at this grade. For example, express 3/10 as 30/100, and add 3/10 + 4/100 = 34/100.

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• 4.NF.A.1

• 4.NF.B.3

## Criteria for Success

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1. Make sense of a three-act task and persevere in solving it (MP.1).
2. Solve word problems involving the addition of decimals and decimal fractions (MP.4).

## Tips for Teachers

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• Note that this lesson includes a mix of decimal and decimal fraction addition problems. If you chose to skip Lesson 11, you should change any word problems involving decimals to decimal fractions in the Anchor Tasks, Problem Set, and Homework.
• Let students work on each problem in the Problem Set independently and circulate to see whether students are solving correctly. If not, come back together to discuss how/what to draw on a tape diagram, then allow them to try again on their own. Encourage students to use a strategy of their choice to assess the reasonableness of their solution.

#### Fishtank Plus

• Problem Set
• Student Handout Editor
• Vocabulary Package

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### Problem 1

(Teachers: Show students the fourth image from the article, "Cool runnings! Bolt helps Jamaica smash world record for astonishing 4x100m relay". Block out the time so students cannot see it.)

Act 1: Look at the image. What is the new world record?

### Problem 2

Act 2: Use the following information to solve -

Mens 4x100m Relay Splits

 Carter 10.16 Frater 9 Blake 8.98 Bolt 8.7

### Problem 3

Act 3: Reveal the answer. (Teachers, show students the full image from the article.)

### Problem 4

Act 4 (the sequel): This new world record was 0.2 faster than the previous world record, also set by the same Jamaican relay team but in 2011. What was the previous world record?

## Discussion of Problem Set

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• What were the two correct answers in #1B? How do you know they are both correct?
• How did you determine how many students chose to play either soccer OR basketball in #3?
• How did you determine the perimeter of the rectangle in #5? Did anyone use fraction multiplication?
• How did you solve #6? What made this more complex than the previous problems?
• Did anyone attempt #7? What made this more complex than the previous problems?

Jay has ${{29\over100}}$ L of oil. He buys another ${1{5\over10}}$ L. He still needs ${{71\over100}}$ L to deep fry clams. How much oil does Jay need to make fried clams?