3.N.2.4 Recognize when to round numbers and apply understanding to round numbers to the nearest ten thousand, thousand, hundred, and ten and use compatible numbers to estimate sums and differences
In a Nutshell
It is necessary that they first learn the accurate rounding procedure; then they will need to identify when to estimate based on key (signal) words and the context of the problem.
Student Actions
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Teacher Actions
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Demonstrate conceptual understanding by building upon the knowledge they have about place value and applying it in more complex mathematical contexts such as rounding numbers accurately.
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Generalize when to round numbers in order to find the estimation of addition and subtraction problems.
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Demonstrate appropriate procedural fluency when adding and subtracting multi-digit numbers using rounding strategies when estimating.
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Communicate mathematically by explaining the process of rounding numbers when problem solving and finding estimations in real life contexts.
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- Pose purposeful questions to help students recall prior knowledge and justify their thinking. Questions may include: When does rounding help us in the real world? Why do we estimate sums/differences? How do we round numbers correctly? How can we prove our answer?
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Implement tasks that give students opportunities to explore numbers and their various representations when rounding.
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Facilitate mathematical discourse that challenges students to connect estimation to other place value concepts.
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Key Understandings
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Misconceptions
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Numbers up to 100,000 can be rounded to the nearest ten thousand, thousand, hundred, or ten.
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Each digit in each of the places has a value and can change when rounding. If the digit to the right of the number you are rounding is 4 or less, the digit will stay the same; if the digit is 5 or more, the number will increase by one, and the digits in the place values behind it will change to zeros. For example: Round 413 to the nearest ten would be 410; round 415 to the nearest ten would be 420; 75,856 round to the nearest hundred would be 75,900.
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Most of the rounding variations of the same number are different from each other. For example: 1,234 can round to 1,000, 1,200, and 1,230.
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That they must round the numbers first before finding the estimation of a sum or difference.
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Estimation is used to help add or subtract quickly.
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They should only look at the digit in the place they are asked to round to. For example: round 1,849 to the nearest hundred, students will say 1,900 because 8 is closer to 9.
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That the only number that changes is the one they are rounding. For example: If they are rounding 486 to the nearest ten, they will say it is 496 vs. 490.
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They cannot round the digit 9 up. Ex: 697 to the nearest ten. They will think it is impossible or try to put a 10 in the middle (6107).
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They are to add or subtract the numbers first, then round the sum or difference after.
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OKMath Framework Introduction
3rd Grade Introduction
3rd Grade Math Standards
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