Divide Whole Numbers by Fractions
I can divide a whole number by a fraction by multiplying by the reciprocal.
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🎯 Content Objective / Objetivo de contenido
I can divide a whole number by a fraction by multiplying by the reciprocal.
Today's Flow
Total pacing: ~45 min · Progress bar at top tracks your place
LAUNCH
⏱ ~10 min
⏱️ 3 MIN · THINK-PAIR-SHARE
Agent Park has 4 pounds of evidence powder and fills bags that hold 1/2 pound each. How many bags can he fill, and how do you know?
Check for Understanding #1
Teacher: If >30% thumbs down, re-teach with a fresh example before moving on.
Detective Agency Case File
Agent Park has 4 pounds of evidence powder. Each testing bag holds exactly 1/2 pound. He needs to prepare as many testing bags as possible before the lab deadline. How many bags can he fill?
Concept Launch
💡 How do I divide a whole number by a fraction?
To divide a whole number by a fraction, you can use Keep, Change, Flip: keep the first number, change divide to multiply, and flip the fraction upside down (its reciprocal). Then multiply.
Dividing by a fraction is the same as multiplying by its reciprocal (the fraction flipped over).
Check for Understanding #2
Teacher: If >30% thumbs down, re-teach with a fresh example before moving on.
Now it's your turn
VOCABULARY
⏱ ~8 min
| Term / Término | Meaning / Significado | Example / Ejemplo | Visual |
|---|---|---|---|
| Whole Number Número entero |
A counting number with no fraction or decimal, like 0, 1, 2, 3. Un número de contar sin fracción ni decimal, como 0, 1, 2, 3. |
4 is a whole number; as a fraction it is 4/1 | |
| Fraction Fracción |
A number that shows part of a whole, like 3/4. Un número que muestra una parte de un todo, como 3/4. |
1/2 means 1 out of 2 equal parts — like cutting a sandwich in half and taking one piece | |
| Reciprocal Recíproco |
A fraction turned upside down. Una fracción volteada de arriba abajo. |
The reciprocal of 2/3 is 3/2. Flip the fraction to divide: 6 ÷ 2/3 = 6 × 3/2 | |
| Keep, Change, Flip Mantener, cambiar, invertir |
A way to divide fractions: keep the first, change ÷ to ×, flip the second. Una manera de dividir fracciones: deja la primera, cambia ÷ por ×, voltea la segunda. |
6 ÷ 1/3 → Keep 6, Change ÷ to ×, Flip 1/3 to 3/1 → 6 × 3 = 18 | |
| Quotient Cociente |
The answer when you divide. La respuesta cuando divides. |
In 4 ÷ 1/2 = 8, the quotient is 8 |
Which Word Fits?
A counting number like 0, 1, 2, or 3 with no fraction or decimal part is a ___.
Use It In a Sentence
Check for Understanding #3
Teacher: If >30% thumbs down, re-teach with a fresh example before moving on.
Turn & Talk — Launch
Agent Park has 4 pounds of evidence powder and fills bags that hold 1/2 pound each. How many bags can he fill, and how do you know?
👂 Listen For
Students see that 4 ÷ 1/2 = 8 and explain there are 2 halves in each whole pound.
Extend: Why does dividing 4 by 1/2 give 8, a number larger than 4, even though you are dividing? Justify.
EXPLORE & PRACTICE
⏱ ~18 min
Visual Modeling Workspace
Use the drawing tray below to annotate the visual model. Teacher: say "Click to reveal" on key steps.
Explore Activity
Use the number line to show how many 1/2-size jumps fit into 4.
✍️ Explore Discourse
Why does 4 ÷ 1/2 = 8? How does the number line show this?
Whiteboard Moment
Show your work clearly. Be ready to explain your thinking to a partner.
Turn & Talk — Explore
How does 'Keep, Change, Flip' turn 6 ÷ 1/3 into a multiplication problem?
👂 Listen For
Students correctly flip the divisor to its reciprocal (3) and explain multiplying by the reciprocal gives the same result as dividing.
Extend: Explain why multiplying by the reciprocal gives the same answer as counting how many 1/3-pieces fit into 6.
Practice Check A
What is 6 ÷ 2/3?
✍️ Show Your Work
Explain why your answer is correct using today's vocabulary.
Practice Check B
What is 6 ÷ 1/3?
✍️ Show Your Work
Explain why your answer is correct using today's vocabulary.
Ratio Table Builder
Fill the ratio table. Each row must be equivalent.
| Factor | A | B |
|---|---|---|
| ×1 | ||
| ×2 | ||
| ×3 |
✍️ Justify Your Thinking
A classmate turned in the work below. One step has a mistake. Read every step, find it, name it, and fix it.
Choose ONE option to show what you know — then do it in the workspace below.
Use evidence from today's lesson to complete each frame.
Today's key idea is: "Dividing by a fraction is the same as multiplying by its reciprocal (the fraction flipped over)." — and it works because ___.
Because Whole Number means ___, but a tricky part is ___, so I have to ___.
A common mistake with Whole Number is ___. It happens because ___, and the fix is ___.
I can prove my answer is correct by ___, using Fraction to check my work.
✍️ TWR · WRITE 3 SENTENCES · 7 MIN
Dividing by a fraction is the same as multiplying by its reciprocal (the fraction flipped over). because ___
Dividing by a fraction is the same as multiplying by its reciprocal (the fraction flipped over). but ___
Dividing by a fraction is the same as multiplying by its reciprocal (the fraction flipped over). so ___
🌱 TWR · GROW THE KERNEL · 6 MIN
Answer these to add detail
Sentence starters (tap to use)
Student Workspace
Use the number line to show how many 1/2-size jumps fit into 4.
| Column A | Column B |
|---|---|
✏️ Sketch Your Strategy
Differentiation Paths
Step-by-step with a worked model and sentence frames.
What is 6 ÷ 1/3?
Core practice aligned to the standard.
Extension with error analysis or multi-step reasoning.
Partner Activity
Work with your partner on the practice problems at your differentiation path level. Explain each step using math vocabulary.
Check for Understanding #4
Teacher: If >30% thumbs down, re-teach with a fresh example before moving on.
Real-World Connection
🌍 Math in the Wild
A detective has 10 feet of rope to section off a crime scene. Each section needs to be 1/4 of a foot long for detailed evidence markers. How many markers can the detective set up?
✍️ Connection Reasoning
How does dividing a whole number by a fraction help the detective?
The detective can set up ___ markers because 10 ÷ 1/4 = ___.
Turn & Talk — Connect
When would dividing a whole number by a fraction help you in real life?
👂 Listen For
Students give a realistic portion/serving scenario and set it up as whole ÷ fraction.
Extend: A student says you should always multiply by the reciprocal to make the answer bigger. Critique this overgeneralization.
CLOSURE & REFLECT
⏱ ~8 min
Today I learned that ___ because ___.
One thing I am still not sure about is ___.
What is 9 ÷ 1/3?
Bonus Exit Check
What is 3 ÷ 1/5?
✍️ Show Your Work
Explain why your answer is correct using today's vocabulary.
Reflection & Self-Assessment
Continue Learning
Launch the Full Interactive Activity
Students continue practice in the HTML lesson engine with auto-check, hints, and differentiation.
Family Connection
Share tonight's family homework and discuss one vocabulary word at home.
Open Family Homework ↗Teacher Notes
⏱️ Pacing Guide
- Launch & vocab: 12 min
- I Do / We Do / You Do: 15 min
- Explore & practice: 15 min
- Connect & closure: 8 min
Total: ~45 min
🎯 Listen For · Common Errors
• Students see that 4 ÷ 1/2 = 8 and explain there are 2 halves in each whole pound.
• Students correctly flip the divisor to its reciprocal (3) and explain multiplying by the reciprocal gives the same result as dividing.
• Students give a realistic portion/serving scenario and set it up as whole ÷ fraction.
• Listen for students naming a specific strategy tied to 6.NS.1 — not just "I multiplied." They should connect steps to the key idea.
Common mistake: A common mistake in Divide Whole Numbers by Fractions is skipping the key idea: "Dividing by a fraction is the same as multiplying by its reciprocal (the fraction flipped over)." — always check your work against this rule before you submit.
Answer Key (Teacher Appendix)
Hide this slide during presentation or move to the end of your copy.
✓ Practice 1: 9 — 6 ÷ 2/3 = 6 × 3/2 = 18/2 = 9. Keep 6, change ÷ to ×, flip 2/3 to 3/2.
✓ Practice 2: 18 — 6 ÷ 1/3 = 6 × 3/1 = 18. There are 18 thirds in 6 wholes.
✓ Practice 3: 15 — 3 ÷ 1/5 = 3 × 5/1 = 15. There are 15 fifths in 3 wholes.
✓ Practice 4: 40 — 10 ÷ 1/4 = 10 × 4/1 = 40. There are 40 quarter-size pieces in 10 wholes.
✓ Exit ticket: 27 — 9 ÷ 1/3 = 9 × 3/1 = 27. There are 27 thirds in 9 wholes.