Addition and subtraction algorithm - summary sheet

Question 47-39= 8
70 - 23 =
638 + 476

What did the student do?

Got the "right" answer 8...
40 - 30, 9-7, 10-2 = 8

Believes 53 she got using her algorithm is correct.
Solves with manipulatives and says, "I don't get it. "
Solves with 100 chart and says, "I don't get it."

600+400=Ten 100
2 ... Whoa! that is way under.
Base ten blocks
Teacher says "One hundred and ten"
Can 1 000 be ten 100's?
Want to do another one? YES PLEASE!

What can be inferred about what the student knows because of what the student did?


Where in your sequence might the student's understanding be among the list of understandings in that sequence? What evidence can you give to support that placement?


What activities, from the book, could be used to build on these student's understanding and move them toward mathematical literacy?



Review the ideas from the Constance Kamii videos for addition and subtraction and describe what you learned about transitioning from single digit addition and subtraction to more advanced additiona and subtraction algorithms to include the traditional algorithms.