I. A subtraction problem set from about 3/4 of the way through the 2nd grade (TERC) Investigations curriculum:
|II. The second half of subtraction problem set from about 1/8 of the way into the 2nd grade Singapore Math curriculum:|
III. Extra Credit
Defenders of Investigations argue that explaining your answers to a smaller number of problems fosters a greater depth of understanding than doing multiple problems using the standard algorithms. How might they explain their answer to America's math woes, and how did they check their answer?