Re: FAST: exemplary middle school science

["RAUBER, JOEL" <JOEL_RAUBER@SDSTATE.EDU>]

One small difference of opinion with Hugh,

> The other quibble has to do with the idea of "expected results." I
> have a running battle with our chemistry teachers who seem to have
> the idea that their students can do error analysis in their labs by
> simply calculating the difference between the answers they obtain and
> the "correct" answer--that is, the answer in the text. This is to
> error analysis as "paint by numbers" is to art.

I believe that when measuring a known quantity, where there exists a
nominally correct value, that calculating per cent error is a legitimate
part of the error analysis.  It provides a good quick reality check on what
you are measuring and can often quickly reveal calculational mistakes.

I hasten to add that this isn't and should never be the complete error
analysis!  Consideration of the error bars, both in a qualitative and
quantitative manner should be viewed as mandatory for interpreting a per
cent error calculation. (I note that quantitative estimation of error bars
is not always easy for students to estimate for labs where  the result is
the end of relatively long chain of calculation).

Joel Rauber