Round Doubloons
10 min
Narrative
The purpose of this Notice and Wonder is for students to share what they know about scales and to initiate a discussion about rounding. The weights on the scale total 12.32 ounces, but the scale reads 12.3 ounces. There are different possible explanations for this discrepancy. For example, the scale might be inaccurate. Or the scale might only give readings in tenths of an ounce. In the discussion, students consider the idea that the value shown on the scale is not always exact. It may show the closest value that it is capable of reading, which is the nearest tenth of an ounce in this case (MP6).
Launch
- Groups of 2
- Display the image.
- “What do you notice? What do you wonder?”
- 1 minute: quiet think time
Teacher Instructions
- “Discuss your thinking with your partner.”
- 1 minute: partner discussion
- Share and record responses.
Student Task
What do you notice? What do you wonder?
Sample Response
Students may notice:
- There are some weights on the scale.
- The weights on the scale total 12.32 ounces.
- The scale reads 12.3 ounces.
Students may wonder:
- Why does the scale not read the 2 hundredths of an ounce?
- Is the scale accurate?
- If I put more 0.01 ounce weights on, what will the scale read?
Activity Synthesis (Teacher Notes)
- “What do you notice about the weights on the scale and the reading of the scale?” (They aren’t the same. The weights are 12.32 ounces and the scale says 12.3 ounces.)
- “Why do you think the scale and the weights don’t agree?” (The scale could be wrong.)
- “What if the scale only shows tenths of an ounce, and it can’t show hundredths of an ounce?” (The value is still not accurate but it’s the best the scale can do.)
- “In today’s lesson we will look at scales that show different numbers of decimals and see how that influences what they show.”
Standards
Building Toward
- 5.NBT.4·Use place value understanding to round decimals to any place.
- 5.NBT.A.4·Use place value understanding to round decimals to any place.
20 min
15 min
Knowledge Components
All skills for this lesson
No KCs tagged for this lesson
Round Doubloons
10 min
Narrative
The purpose of this Notice and Wonder is for students to share what they know about scales and to initiate a discussion about rounding. The weights on the scale total 12.32 ounces, but the scale reads 12.3 ounces. There are different possible explanations for this discrepancy. For example, the scale might be inaccurate. Or the scale might only give readings in tenths of an ounce. In the discussion, students consider the idea that the value shown on the scale is not always exact. It may show the closest value that it is capable of reading, which is the nearest tenth of an ounce in this case (MP6).
Launch
- Groups of 2
- Display the image.
- “What do you notice? What do you wonder?”
- 1 minute: quiet think time
Teacher Instructions
- “Discuss your thinking with your partner.”
- 1 minute: partner discussion
- Share and record responses.
Student Task
What do you notice? What do you wonder?
Sample Response
Students may notice:
- There are some weights on the scale.
- The weights on the scale total 12.32 ounces.
- The scale reads 12.3 ounces.
Students may wonder:
- Why does the scale not read the 2 hundredths of an ounce?
- Is the scale accurate?
- If I put more 0.01 ounce weights on, what will the scale read?
Activity Synthesis (Teacher Notes)
- “What do you notice about the weights on the scale and the reading of the scale?” (They aren’t the same. The weights are 12.32 ounces and the scale says 12.3 ounces.)
- “Why do you think the scale and the weights don’t agree?” (The scale could be wrong.)
- “What if the scale only shows tenths of an ounce, and it can’t show hundredths of an ounce?” (The value is still not accurate but it’s the best the scale can do.)
- “In today’s lesson we will look at scales that show different numbers of decimals and see how that influences what they show.”
Standards
Building Toward
- 5.NBT.4·Use place value understanding to round decimals to any place.
- 5.NBT.A.4·Use place value understanding to round decimals to any place.