Re: apples and oranges

[Mervin Koehlinger <tchkoehlimw@crf.cuis.edu>]

On Sun, 1 Nov 1998, David W. Steyert wrote:

> I'd like to learn from the group how we get students across that divide:
> from concrete science problem to the equation they need to solve... and
> back to the scientific interpretation.

Require students to write down their thought process as they solve a
problem.

For example, here's a simple problem: "How many minutes will it take a car
traveling 30 m/s to go 100 km?"

Here's an example of the thought process necessary to solve it.

1.  The car must travel 100 km.
2.  There are 1000 m in 1 km.
3.  The car must travel 1000 m 100 times, or 100 000 m.
4.  The car can travel 30 m in 1 s.
5.  In order to travel 100 000 m, it must travel 30 m 100 000/30 = 3333
times.
6.  The car must travel for 3333 s.
7.  There are 60 s in 1 min.
8.  The car must travel for 3333/60 = 56 min.

Of course, students absolutely detest having to do this, but if they can't
explain a simple solution in this way, then it's simple to see why they
can't solve more difficult problems.

Mervin Koehlinger
Physics Instructor
Concordia Lutheran High School
Fort Wayne, Indiana