Grade 6 Mathematics · Unit 2: Understanding the World Around Us Through StatisticsStandard 6.NOS.3

Lesson 2.11Add and Subtract Decimals

Set B · Version ASecond form · supported practice

Mastery check☐ Exceeds☐ Meets target☐ Needs practice
Name Date Period

Learning target I can add and subtract decimals by lining up the place values and the decimal points.

Why This Matters The space station's main fuel tank reads 128.75 liters. A resupply shuttle delivers 46.8 liters of fuel, but the thrusters used 19.35 liters during docking. What is the fuel level after both events?

RememberAdd and Subtract Decimals

Adding & Subtracting Decimals A decimal is a number with a point that shows parts smaller than one whole. To add or subtract decimals, you line up the decimal points so the same place values match.

  1. Line up the decimal points vertically by place value.
  2. Insert placeholder zeros so each number has the same number of decimal digits.
  3. Add or subtract right-to-left, regrouping as needed, and drop decimal straight down

Words: Decimal (Decimal)Place value (Valor posicional)Tenths (Décimas)Hundredths (Centésimas)Annex zeros (Agregar ceros)

  1. 1Circle the letter of the best answer. Show how you know.

    A data set has one very large outlier. Which measure of centre does it pull on MORE?

    1. AThe median
    2. BNeither one
    3. CThe mean
    4. DBoth equally
    Show your work
  2. 2Circle the letter of the best answer. Show how you know.

    House prices on a street are $180,000, $190,000, $200,000, $210,000 and $2,000,000. Which measure best describes a typical price?

    1. AThe mean
    2. BThe median
    3. CThe range
    4. DThe largest value
    Show your work
  3. 3Circle the letter of the best answer. Show how you know.

    A data set is roughly symmetric with no outliers. Which measure of centre is a good choice?

    1. AThe range
    2. BOnly the maximum
    3. CThe mean
    4. DNeither the mean nor the median
    Show your work
  4. 4Circle the letter of the best answer. Show how you know.

    Test scores are 70, 72, 75, 74 and 12. Find the median.

    1. A60.6
    2. B72
    3. C74
    4. D75
    Put the data in order
    Work
    1. 1OrderSmallest to largest.
    2. 2CountHow many values?
    3. 3LocateMiddle, or add and divide.
    4. 4AnswerSay which measure it is.
  5. 5Circle the letter of the best answer. Show how you know.

    A runner's times for three laps are 2.45 minutes, 2.6 minutes, and 2.38 minutes. She wants to find her total time to see if she beat her personal record of 7.5 minutes. 2.45 + 2.60 + 2.38 = ?

    1. A6.43
    2. B7.143
    3. C7.43
    4. D7.53
    Line up the place values
    1. 1Line upPoints under points.
    2. 2Fill gapsWrite in the zeros.
    3. 3OperateRight to left.
    4. 4Bring the point downStraight down.
  6. 6Circle the letter of the best answer. Show how you know.

    A runner's times for three laps are 2.45 minutes, 2.6 minutes, and 2.38 minutes. She wants to find her total time to see if she beat her personal record of 7.5 minutes. Why is it safe to rewrite 2.6 as 2.60?

    1. AIt makes the number ten times bigger
    2. BAdding a zero at the end of a decimal does not change its value
    3. CIt rounds the number up
    4. DBecause 6 and 60 use the same digit
    Show your work

Explain your thinkingHow does a number line help you see what happens when you add or subtract decimals?

Sentence starter When I add ___ to ___, I move ___ to the right on the number line and land on ___.

3-Point Exit Checklist: ☐ 1. Units & Labels Verified ☐ 2. Mathematical Reasoning Stated ☐ 3. Calculations Double-Checked
How did it go? ☐ 4 · I can teach it☐ 3 · I've got it☐ 2 · I need a hint☐ 1 · I need help
Grade 6 Mathematics · Unit 2: Understanding the World Around Us Through StatisticsStandard 6.NOS.3

Lesson 2.11Add and Subtract Decimals

Set B · Version BSecond form · core practice

Mastery check☐ Exceeds☐ Meets target☐ Needs practice
Name Date Period

Learning target I can add and subtract decimals by lining up the place values and the decimal points.

Why This Matters The space station's main fuel tank reads 128.75 liters. A resupply shuttle delivers 46.8 liters of fuel, but the thrusters used 19.35 liters during docking. What is the fuel level after both events?

Part 1Understand the ideamodels and meaning
  1. 1Write the letter of the matching item on each line.

    Match each receipt or log expression to its correct sum or difference.

    1. 18.4 + 6.95
    2. 22.5 − 9.8
    3. 7.06 + 3.4
    4. 40 − 13.55
    5. 16.2 − 9.65
    • A25.35
    • B12.7
    • C10.46
    • D26.45
    • E6.55
  2. 2Write the name of the correct group on each line.

    Estimate each receipt total by rounding to the nearest whole dollar, then sort: was the exact result more than $20 or less than $20?

    Groups: More Than $20 Less Than $20
    • $13.40 + $9.75
    • $30.00 − $4.85
    • $11.60 + $8.99
    • $12.75 − $3.40
    • $6.50 + $7.25
    • $25.10 − $7.45
Part 2Apply itreal-world problems
  1. 3Circle the letter of the best answer. Show how you know.

    A runner's times for three laps are 2.45 minutes, 2.6 minutes, and 2.38 minutes. She wants to find her total time to see if she beat her personal record of 7.5 minutes. Did she beat her personal record of 7.5 minutes?

    1. ANo, because 7.43 > 7.5
    2. BYes, because 7.43 < 7.5
    3. CNo, because 7.43 and 7.5 are equal
    4. DYou cannot compare them
    Show your work
  2. 4Circle the letter of the best answer. Show how you know.

    Case File: A crew member's snack receipt shows $27.60 for dried fruit and $15.45 for protein bars. What is the total on the receipt?

    1. A$42.05
    2. B$42.95
    3. C$43.05
    4. D$43.15
    Show your work
  3. 5Circle the letter of the best answer. Show how you know.

    Case File: The oxygen gauge dropped from 9.6 units to a new reading after the crew used 4.75 units. How much oxygen is left?

    1. A4.85
    2. B4.95
    3. C5.15
    4. D5.85
    Show your work
  4. 6Circle the letter of the best answer. Show how you know.

    Case File: A supply log started the shift with $48.00 in the station snack fund. By the end, $31.27 had been spent. How much is left in the fund?

    1. A$16.73
    2. B$16.83
    3. C$17.27
    4. D$17.73
    Show your work

Explain your thinkingHow does a number line help you see what happens when you add or subtract decimals?

3-Point Exit Checklist: ☐ 1. Units & Labels Verified ☐ 2. Mathematical Reasoning Stated ☐ 3. Calculations Double-Checked
How did it go? ☐ 4 · I can teach it☐ 3 · I've got it☐ 2 · I need a hint☐ 1 · I need help