Maria
Manipulatives
= 100
Called a flat 
= 10
Called a long 
= 1
Called a single 



Maria uses manipulatives (baseten 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."

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's name, and then explain your choice.
3.3 Consider just the strategies on which you
would focus in a unit on multidigit addition. Over a severalweeks' unit,
in which order would you focus on these strategies?
First:


Second:


Third:


Fourth:


Fifth:


Please explain your answer for the rankings in 3.3 above.
3.4. Do you think that
Carlos could make sense of and explain Sarah's strategy? Why or why not? 
3.5. Do you think that Carlos could make
sense of and explain Elliott's strategy? Why or why not?

