Lexi

                 ⁵6¹3 5

               –  4 8 2

                   1 5 3

Lexi says, "First I subtracted 2 from 5 and got 3. Then I couldn't subtract 8 from 3, so I borrowed. I crossed out the 6, wrote a 5, then put a 1 next to the 3. Now it's 13 minus 8 is 5. And then 5 minus 4 is 1, so my answer is 153."

Ariana

635 –  400  =  235

235 –    30 =   205

205 –    50 =   155

155 –      2 =   153

           482        

Ariana says, "First I subtracted 400 and got 235. Then I subtracted 30 and got 205, and I subtracted 50 more and got 155. I needed to subtract 2 more and ended up with 153."

4.1 Does Lexi's reasoning make sense to you?

Yes    No

4.2 Does Ariana's reasoning make sense to you?

  Yes    No

4.4  Describe how Lexi would solve this item:  700 – 573.

4.5 Describe how Ariana would solve this item:  700 – 573.