Divide to Multiply Unit Fractions
10 min
Narrative
The purpose of this Estimation Exploration is for students to practice estimating a given length on a number line. Students are given the length of a longer segment as a point of reference and apply their understanding of equal parts to the number line to estimate a shorter length.
Launch
- Groups of 2
- Display the image.
- “What number could go in the box? What is an estimate that’s too high? Too low? About right?”
- 1 minute: quiet think time
Teacher Instructions
- “Discuss your thinking with your partner.”
- 1 minute: partner discussion
- Record responses.
Student Task
What number is marked on the number line?
Record an estimate that is:
| too low | about right | too high |
|---|---|---|
Sample Response
Sample responses:
- Too low: 21 to 1
- About right: 141 to 2
- Too high: 221 to 3
Activity Synthesis (Teacher Notes)
- “Is the number that goes in the box more or less than half of 5? How do you know?” (Less, since it is less than half the way to 5.)
- “How does this help you estimate the value?” (I know half of 5 is 221, so it is less than that.)
- Optional: Reveal the actual value and add it to the display.
Standards
- 5.NF.4·Apply and extend previous understandings of multiplication to multiply a fraction or whole number by a fraction.
- 5.NF.B.4·Apply and extend previous understandings of multiplication to multiply a fraction or whole number by a fraction.
20 min
15 min
Knowledge Components
All skills for this lesson
No KCs tagged for this lesson
Divide to Multiply Unit Fractions
10 min
Narrative
The purpose of this Estimation Exploration is for students to practice estimating a given length on a number line. Students are given the length of a longer segment as a point of reference and apply their understanding of equal parts to the number line to estimate a shorter length.
Launch
- Groups of 2
- Display the image.
- “What number could go in the box? What is an estimate that’s too high? Too low? About right?”
- 1 minute: quiet think time
Teacher Instructions
- “Discuss your thinking with your partner.”
- 1 minute: partner discussion
- Record responses.
Student Task
What number is marked on the number line?
Record an estimate that is:
| too low | about right | too high |
|---|---|---|
Sample Response
Sample responses:
- Too low: 21 to 1
- About right: 141 to 2
- Too high: 221 to 3
Activity Synthesis (Teacher Notes)
- “Is the number that goes in the box more or less than half of 5? How do you know?” (Less, since it is less than half the way to 5.)
- “How does this help you estimate the value?” (I know half of 5 is 221, so it is less than that.)
- Optional: Reveal the actual value and add it to the display.
Standards
- 5.NF.4·Apply and extend previous understandings of multiplication to multiply a fraction or whole number by a fraction.
- 5.NF.B.4·Apply and extend previous understandings of multiplication to multiply a fraction or whole number by a fraction.