Maria
Manipulatives
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= 100
Called a flat
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= 10
Called a long
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= 1
Called a
single
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Maria uses manipulatives (base-ten
blocks) to solve the problem. Maria says, "I took one
flat for the 100 in 149 and 2 flats for the 200 in
286.
I took 12 longs: 4 for the 40 in 149
and 8 for the 80 in 286.
I took 15 singles for the 9 in 149 and
the 6 in 286.
Then I counted like this, '100, 200,
300'; then for the longs, '310, 320, 330, 340, 350, 360,
370, 380, 390, 400, 410, 420'; then the singles, '421,
422, 423, 424, 425, 426, 427, 428, 429, 430, 431, 432,
433, 434, 435.'
So the answer is 435."
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3.2. If you were a teacher, which of
the approaches would you like to see children share?
Select "yes" or "no" next to each student and then
explain why or why not.
3.3 Consider just the strategies on which you would
focus in a unit on multidigit addition. Over a
several-weeks unit, in which order would you focus on
these strategies?
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First:
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Second:
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Third:
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Fourth:
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Fifth:
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Please explain your answer for the rankings in 3.3
above.
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3.4. Do you think that
Carlos could make sense of and explain Sarah's
strategy? Why or why not?
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3.5. Do you think that Carlos
could make sense of and explain Elliott's
strategy? Why or why not?
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