>In addition, to teach students some "real world problems" that require >the skills of complicated calculation ( as norm proposed ) which they >are not yet able to even visualize in their head is to confuse >students. In K-4, I do not see any appropriate need of calculator in >math class that will not be abusive. >
Can a second grader visualize 1,375,472 + 3,125,528? Perhaps not. So, by your argument, we should perhaps avoid confusion and not allow them to work with such numbers.
Personally, I can't visualize numbers in the trillions, even though the United States' national debt is among such enormous numbers. Yet, I feel I can solve problems that deal with these large numbers, without becoming confused.