Bundling and Unbundling
Task
Make true equations. Write one number in every space. Draw a picture if it helps.
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1 hundred + 4 tens = ______
4 tens + 1 hundred = ______
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14 tens = 10 tens + _____ tens
14 tens = _____ hundred + 4 tens
14 tens = _____ ones
- 7 ones + 5 hundreds = ______
- 8 hundreds = ______
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106 = 1 hundred + _____tens + _____ones
106 = _____tens + _____ones
106 = _____ones
- 90 + 300 + 4 = ______
IM Commentary
Students determine the number of hundreds, tens and ones that are necessary to write equations when some digits are provided. Student must, in some cases, decompose hundreds to tens and tens to ones. The order of the summands does not always correspond to the place value, making these problems less routine than they might seem at first glance.
See the solution for detailed information about the parts of this task.
Solution
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140, 140.
The first problem asks for the same number (140) in different ways. This emphasizes that order doesnât matter in addition â yet order is everything when using place-value notation.
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14 tens = 10 tens + 4 tens
14 tens = 1 hundred+4 tens
14 tens = 140.
In this problem, the baseâten units in 140 are bundled in different ways. In the first line, âtensâ are thought of as units: 14 things = 10 things + 4 things.
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507.
By scrambling the usual order, the third problem requires students to link the values of the parts with the order of the digits in the positional system. Also, to encode the quantity, the student will have to think: âno tens,â emphasizing the role of 0.
7 ones + 5 hundreds = 507
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800.
In the fourth problem, the zeros come with a silent âno tens and no onesâ:
8 hundreds = 800
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106 = 1 hundred + 0 tens + 6 ones
106 = 10 tens + 6 ones
106 = 106 ones
In this problem, the base-ten units in 106 are bundled in different ways. This is helpful when learning how to subtract in a problem like 106 â 34 by thinking about 106 as 100 tens and 6 ones.
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394.
The sixth problem is meant to illustrate the notion that If the order is always given âcorrectly,â then all we do is teach students rote strategies without thinking about the size of the units or how to encode them in positional notation.
90 + 300 + 4 = 394
Bundling and Unbundling
Make true equations. Write one number in every space. Draw a picture if it helps.
-
1 hundred + 4 tens = ______
4 tens + 1 hundred = ______
-
14 tens = 10 tens + _____ tens
14 tens = _____ hundred + 4 tens
14 tens = _____ ones
- 7 ones + 5 hundreds = ______
- 8 hundreds = ______
-
106 = 1 hundred + _____tens + _____ones
106 = _____tens + _____ones
106 = _____ones
- 90 + 300 + 4 = ______