I’d love to hear anything that you’re thinking about this in the comments.
I wonder: should we be giving kids explicit guides for these sorts of algorithms at all? Algorithms ought to be patterns in thought. Does a mistake like this begin to make a case against these sort of printed aids?
Thanks to Professor Triangleman for the submission.
From the submitter: “I came across these answers to sig fig questions when marking a pre-algebra numeracy test last night. I’ve attached two answers, one is a very common mistake where students just can’t believe that they are asked to round up that much. The second… well I don’t have any idea what the student was thinking, so I thought your readers might be able to help.”
How did this kid come to believe in this algorithm?
Thanks to Amy Burk for the submission.