geom25 question

 

geom 25

 

geom 25 2 (800x648)

 

What other mistakes would you expect to see from this problem? How do you teach so as to help students avoid these pitfalls?

Thanks to Tina Cardone for the submission.

  • I figured out how the student got 23.32! They found 20, using the Pythagorean theorem, and then they used it again in the Pythagorean theorem with 12. I’m not sure WHY they did that, but at least I know where the number comes from.

    The second student sure looks like they are guessing for part c.

    • I find a surprising number of students who think they can count diagonal distances either by counting on the diagonal (for slope 1) or picking horizontal/vertical distance. This kid may have said “up 16” and decided they were done.