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Re: [Phys-L] Sig Figs homework from my 7th grader



I am not sure I know the answer the teacher wants without seeing a written
out set of rules that the student is supposed to use. The big problem is
that there is no general agreement on what the answer might be.

Sig figs can be used as a way to help students understand uncertainty. It
may even work better with concrete operational reasoners. The usual error
analysis will be very opaque to them. The big problem is that most books
just give rules without having the students explore why those rules may have
some validity. Notice I said "some". Sig figs are certainly not the best
way to treat uncertainty.

The big problem is the dogmatic following of rules without having students
understand them.

I was once in a class where they tuaght students how to calculate STD. The
instructor had the students round off the numbers before doing the
calculation. Of course unrounded numbers yielded a slightly different
answer. So I had to conform to his method. The easy way was to just enter
the numbers in my scientific calculator and have it do all the drudge work,
but that yielded the "wrong" answer. I was nice and did not challenge the
instructor who looked to be very close to retirement. A lot of the other
students had no clue as to the meaning of STD, as most were not going to be
either math or science teachers. It is amazing the drudge work you have to
do to be certified!

John M. Clement
Houston, TX


I know the answer the teacher wants, but i find it troubling...

10.53 + 0.615 = ?

Share and enjoy,
Paul
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