LEARN NC

Problem centered math

Developed by LEARN NC with Grayson Wheatley

1.7 Toy cars problem

6 toy cars can be parked in a row 16 inches long. How many cars can be parked in a row 64 inches long? 240 inches long?

Watch the interview

You must have javascript and Flash Player to play this video.


Download video (Right-click or option-click)

Transcript

Grayson
I would like for you to look at this one. Read that top problem, please.
Student
6 toy cars can be parked in a row 16 inches long. How many cars can be parked in a row 64 inches long? And, then 240 inches long.
Grayson
First just…
Student
So 6 could be parked…
Grayson
OK, so you set up 6 over 16
Student
and x over 64. Then I would do 6 times 4, 24, and just do…6 times 6 equals 36, 6 time times 3 is 6 times 4 is 18.
Grayson
Let’s say with 64 on the top and 6 on the bottom.
Student
4 6’s, 18
Grayson
24
Student
736
Grayson
OK, you got…
Student
384
Grayson
Yes and that is the result of multiplying 6 times 64.
Student
And, then we would do 384 divided by 16.
Grayson
OK, we won’t carry that out, but then this result you would get would be…your answer is to how many cars we could park. Just looking at that, estimate how many we could park.
Student
2 or 3.
Grayson
2 or 3 cars?
Student
um hmm.
Grayson
Oh, well we have some other questions, so we won’t carry this out.
Student
Well actually you’ve got that then. How would you be…16, 14
Grayson
16 or 14. OK so it would be about 16 or 14 cars that could be parked in there. OK, good.

The student’s work

Analysis

The student can set up a proportion equation and solve it if she does not make a computational error. However, if an error is made, she would not recognize an inappropriate answer. When asked to estimate how many cars could be parked, she says 14 or 16 — not a good estimate. Again her procedural orientation is evident and debilitating.