I agree with the views of several who question the usefulness of
teaching significant digits in the way that is typically done in
introductory science classes. However, I do want the students in my
High School Physics class to walk away with at least two ideas for them
to begin to ponder.
1) What is a significant digit? A digit with significance! I remember
agonizing through many months of chemistry before I realized this simple
fact. One bright but inexperienced sophomore said this week, "I like to
use all of the digits in my display because that gives me the most
accurate answer." Yesterday as he was leaving class he said "Wow this
class is really making me look at things from a different angle." This
new view of the digits on his calculator was only one of many new ideas
but I think an important one.
2) 123 can in many cases can have exactly the same meaning as 122 or 124
etc. Given their experience in math classes this is an idea they
resist. The whole concept of carrying meaning through their mathematics
is an idea that is not well developed in their minds. This is a start.
I like using the first few days of the year with ideas like these
because many students are not ready to truly begin thinking hard yet.
Too much excitement and confusion in the first few days. The brighter
students can take these ideas and run with them and those less motivated
or able have not missed anything they absolutely can not live without as
they begin to settle in.