Open thread. Talk about what you find interesting here, or anything. I’ll kick things off in the comments.

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- Post author By mpershan
- Post date October 30, 2013
- 7 Comments on 103 > 130 and Other Mistakes

## 7 replies on “103 > 130 and Other Mistakes”

Can we trust that this kid knows what “>” and “<" mean? I think so. There's reliability in 231 < 321, 97 < 899 and the last question. Which leaves a puzzle: how do you mess up 103 > 130 if not for the “>” operation?

I’m stumped. Maybe the kid doesn’t really have comfort with “>” after all. Otherwise, not sure.

D’oh!

Totally misread the kid’s work. #BloggerMistakeDotOrg

I think the student got the 103 > 130 as false just fine. What they’re missing is that things in the hundreds place don’t necessarily trump things in the tens place, in the unusual case where you are allowed to have more than 9 groups of ten. This is an interesting idea about understanding of place value and regrouping! I mean, ordinarily you can assume that the value of whatever’s in the most significant digit wins over anything in the remaining digits, but not when you’ve regrouped to have more than 9 as one of the “digits”.

I was going to say the test format was throwing the student, as it was me- otherwise looks like the regrouping errors are due to mental math mistakes.

I blew through 831=…. without reading passed 700. Could be same is true for student

I did the same. Perhaps it was an instance of rushing and not reading the entire question rather than a misunderstanding of comparing values.

It also seems that he is more comfortable with statements of the a

b form. Is there something going on with the direction of the inequality? I stubbornly write all my inequalities in the a < b form so I can refer back to the number line over and over again.