Practice Set · Part 1
Division Expressions with Fractions and Whole Numbers
Pick up where we left off
Where we left off
Our goal: With my small group, I can use models to divide a whole number by a fraction and a fraction by a whole number — one step at a time, with support.
The big idea: Dividing by a fraction asks how many pieces fit. Write the whole number over 1, then Keep, Change, Flip, and multiply.
Model to copy — Example 1 · Whole number ÷ unit fraction
- A strip of tape is 3 feet long. You cut it into pieces that are 1/4 foot long. How many pieces do you get? Find 3 ÷ 1/4.
- Write the division: 3 ÷ 1/4
- Put a 1 under the whole number: 3/1 ÷ 1/4
- Keep, Change, Flip: 3/1 × 4/1
- Multiply the tops. Multiply the bottoms: 3/1 × 4/1 = 12/1 = 12
- 3 ÷ 1/4 = 12. You get 12 pieces of tape.
- You have 3/4 foot of tape. You cut it into 2 equal pieces. How long is each piece? Find 3/4 ÷ 2.
- Put a 1 under the whole number: 3/4 ÷ 2/1
- Keep, Change, Flip: 3/4 × 1/2
- Multiply the tops. Multiply the bottoms: 3/4 × 1/2 = 3/8
- 3/4 ÷ 2 = 3/8. Each piece is 3/8 foot long.
Start here
You did these with your group. Now do them on your own — the model above is yours to copy.
- 1
Same stepsFinish what the group started. Use the model above, step for step.
Let's do one together: Find 2 ÷ 1/3. How many thirds fit in 2 wholes? Put a 1 under the whole number. What do you get? (2/1 ÷ 1/3) Keep, Change, Flip. What is the new problem? (2/1 × 3/1) Multiply across. What is the answer? (2/1 × 3/1 = 6/1 = 6) Count the thirds in the bars. Do you get the same number? (Yes. There are 6 thirds in 2 wholes.)My first step is ___ , because the problem asks for ___ .
Show your work - 2
Warm restartWhat is 4.8 ÷ 2?
- A0.24
- B2.4
- C2.6
- D24
- 3
Warm restartWhat is 8.4 ÷ 0.7?
- A0.12
- B1.2
- C12
- D120
- 4
Warm restartWhat is 14.4 ÷ 1.2?
- A0.12
- B1.2
- C12
- D120
Practice Set · Part 2
Division Expressions with Fractions and Whole Numbers
Keep going
You answered these out loud. Now write them.
Answer, then say how you know — the reason is the part that counts.
- 5
Think it through6 ÷ 1/3 = ?
- A2
- B3
- C6
- D18
Why is that the answer?
I chose ___ because ___ .
- 6
Think it throughWhy is the answer bigger than 6?
- ABecause the pieces are smaller than a whole yard, so many of them fit
- BBecause dividing always makes numbers bigger
- CBecause 1/3 is negative
- DBecause 6 × 3 is multiplication, not division
How do you know?
I chose ___ because ___ .
- 7
Think it throughIf each section were 1/2 yard instead, how many sections?
- A3
- B12
- C18
- D24
Explain your thinking.
I chose ___ because ___ .
- 8
Back to the modelWhy does dividing by a unit fraction always give a number larger than the dividend?
Dividing by 1/3 means finding how many ___ fit into ___, so the quotient is ___ than the dividend.
Practice Set · Part 3
Division Expressions with Fractions and Whole Numbers
Words and reasoning
Word bank · Banco de palabras
Use the words
Fill each blank with a word from the bank.
- In 6 ÷ 1/2, the number 6 being divided is the ___.
- In 6 ÷ 1/2, the number 1/2 we divide by is the ___.
- The answer to a division problem is the ___.
- The fraction you get by flipping the numerator and denominator is the ___.
Explain the thinking
- 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 Interpret Division of Fractions is assuming that dividing always makes the answer smaller. - 10
Say moreWhat does 3 ÷ 1/4 actually mean? Show your partner with the bar model.
Dividing 3 by 1/4 means finding how many ___ fit into ___.
- 11
Change one numberGo back to Part 1 and pick one problem you already solved. Change one number in it, then solve your new version. Show every step.
If ___ changed to ___ , then ___ .
Show your work
Practice Set · Part 4
Division Expressions with Fractions and Whole Numbers
Show what you know
Last check
These two come from Lesson 5.10. If they are shaky, that is the lesson to revisit — not this one.
- 12
Show what you knowQuick check — you've got this: What does 5 ÷ 1/4 mean, and what is the quotient?
- AHow many 1/4-size pieces fit into 5; quotient is 20
- B1/4 of 5; quotient is 5/4
- C5 groups of 1/4; quotient is 5/4
- D5 minus 1/4; quotient is 4 3/4
Explain your choice.
I know it is ___ because ___ .
- 13
From Lesson 5.10Quick check — you've got this: A rectangular prism has l = 7 ft, w = 2 ft, h = 3 ft. What is the volume?
- A12 ft³
- B24 ft³
- C42 ft³
- D42 ft²
- 14
From Lesson 5.10Why divide by 231 instead of multiplying?
- ABecause dividing always makes numbers smaller
- BBecause you are finding how many 231-in³ gallons fit inside the tank
- CBecause 231 is bigger than 24
- DBecause gallons are bigger than inches
Be honest — this tells your teacher what to do next
| I can… | Not yet | Getting there | Got it |
|---|---|---|---|
| I can use models to divide a whole number by a fraction and a fraction by a whole number — one step at a time, with support. | |||
| I can explain why it works: Dividing by a fraction asks how many pieces fit. Write the whole number over 1, then Keep, Change, Flip… | |||
| I can talk through each step out loud using a sentence frame and the lesson's key words. |
One question I want to ask my group next time