6.NOS.1 Group 2 · Challenge

Practice Set · Part 1

Divide Whole Numbers by Fractions

Pick up where we left off

Name: Date: Group:

Where we left off

Our goal: I can divide a whole number by a fraction by multiplying by the reciprocal, explain why the method works, and use it on a problem I have not seen before.

The big idea: Multiply by the reciprocal to divide, and read a fraction in the answer as part of one more group.

Model to copy — Example · The answer has a leftover

  1. Maya has 5 yards of ribbon. Each bow uses 3/4 yard. How many full bows can she make? How much ribbon is left?
  2. Write the division: 5 ÷ 3/4
  3. Multiply by the reciprocal of 3/4: 5 × 4/3 = 20/3
  4. Change 20/3 to a mixed number: 20/3 = 62/3
  5. Find the ribbon left after 6 bows: 6 × 3/4 = 18/4 = 41/2; 5 − 41/2 = 1/2
  6. She can make 6 full bows. 1/2 yard of ribbon is left.

Start here

You did these with your group. Now do them on your own — the model above is yours to copy.

  1. 1

    Same stepsFinish what the group started. Use the model above, step for step.

    Try it together — then prove it: Find 3 ÷ 1/4. Then explain why the answer is greater than 3. Rewrite 3 ÷ 1/4 as a multiplication. (3 × 4) What is the quotient? (3 × 4 = 12) Why is 12 greater than 3? (The pieces are smaller than 1 whole. Each whole holds 4 pieces, so 3 wholes hold 12.)
    Show your work
  2. 2

    Warm restartWhich property is shown? 7 × 5 = 5 × 7

    1. AAssociative Property
    2. BIdentity Property
    3. CCommutative Property
    4. DDistributive Property

    How do you know?

  3. 3

    Warm restartWhich property is shown? (2 + 9) + 1 = 2 + (9 + 1)

    1. AAssociative Property
    2. BCommutative Property
    3. CIdentity Property
    4. DDistributive Property

    How do you know?

  4. 4

    Warm restartWhich grouping makes 4 × 25 × 7 easiest to multiply mentally?

    1. A(4 × 25) × 7
    2. B4 × (25 + 7)
    3. C(4 + 25) × 7
    4. D(25 × 7) × 4

    How do you know?

6.9 Small Group · Group 2 · Practice SetPart 1 of 4
6.NOS.1 Group 2 · Challenge

Practice Set · Part 2

Divide Whole Numbers by Fractions

Keep going

You answered these out loud. Now write them.

Answer, then say how you know — the reason is the part that counts.

  1. 5

    Think it through10 ÷ 1/4 = ?

    1. A2.5
    2. B4
    3. C14
    4. D40

    Why is that the answer?

  2. 6

    Think it throughWhat is the reciprocal of 1/4?

    1. A1/4
    2. B−1/4
    3. C1/2
    4. D4

    How do you know? Give a second reason as well.

  3. 7

    Think it throughA student answered 2.5. What did they do wrong?

    1. AThey multiplied by 4
    2. BThey added 1/4
    3. CThey used the wrong rope length
    4. DThey divided by 4 instead of by 1/4

    Explain your thinking. What would have to change for a different choice to be right?

  4. 8

    Back to the modelWhy does 3 ÷ 1/4 = 12? How does the number line show this?

6.9 Small Group · Group 2 · Practice SetPart 2 of 4
6.NOS.1 Group 2 · Challenge

Practice Set · Part 3

Divide Whole Numbers by Fractions

Words and reasoning

Word bank · Banco de palabras

Whole Number (Número entero)Fraction (Fracción)Reciprocal (Recíproco)Keep, Change, Flip (Mantener, cambiar, invertir)Quotient (Cociente)

Use the words

Fill each blank with a word from the bank.

Explain the thinking

  1. 9

    Find the mistakeAnother student made this exact mistake in this lesson. Explain why it is wrong, then write what they should have done.

    The mistake: A common mistake in Divide Whole Numbers by Fractions is doing 'Keep, Change' but skipping the 'Flip' — students multiply by the divisor as it is instead of by its reciprocal.
  2. 10

    Say moreHow does 'Keep, Change, Flip' turn 6 ÷ 1/3 into a multiplication problem?

  3. 11

    Write your ownWrite your own problem about this situation, then solve it and show the answer. The situation: A STEM summer camp has a 3-hour afternoon session. Campers choose from afternoon activities that are each 45 minutes long.

    Show your work
6.9 Small Group · Group 2 · Practice SetPart 3 of 4
6.NOS.1 Group 2 · Challenge

Practice Set · Part 4

Divide Whole Numbers by Fractions

Show what you know

Last check

These two come from Lesson 6.8. If they are shaky, that is the lesson to revisit — not this one.

  1. 12

    Show what you knowExplain your thinking — What is 9 ÷ 1/3?

    1. A1/27
    2. B3
    3. C9/3
    4. D27

    Explain your choice.

  2. 13

    From Lesson 6.8Explain your thinking — Which property is shown? (8 + 5) + 2 = 8 + (5 + 2)

    1. AAssociative Property
    2. BCommutative Property
    3. CIdentity Property
    4. DDistributive Property

    How do you know?

  3. 14

    From Lesson 6.8What is 4 × 17 × 25?

    1. A170
    2. B425
    3. C1,000
    4. D1,700

    How do you know?

Be honest — this tells your teacher what to do next

I can…Not yetGetting thereGot it
I can divide a whole number by a fraction by multiplying by the reciprocal, explain why the method works, and use it on a problem I have not seen before.
I can explain why it works: Multiply by the reciprocal to divide, and read a fraction in the answer as part of one more group.
I can justify my answer to a skeptic and connect it to a second strategy or representation.

One question I want to ask my group next time