Uncertainty
of Experimental Data:
One
of the most important and also one of the most basic concepts beginning science
students need to learn is often overlooked. It is that the results of any
scientific experiment always have a degree of uncertainty. Nature never lies,
but the scientists' ability to conduct the experiment, measure, and interpret
the results is predictably imperfect. How many times have you conducted an
experiment and felt lucky to have gotten 60% yield? Almost anything can cause
error in experimental results: a concentration that is inexact, a scale that
only displays to the 1/100 of a gram, a shaky hand or the limits of hand-eye
coordination in a timing experiment. Students understand the idea of error in
experimental data on a basic level even from their first lab, but they tend to
see it as the fault of their inexperience-and don't think it through
enough to generalize the concept to include all scientific processes. It is
generalization and bringing the concept to the conscious mind that needs to be
taught.
Students
should know that even the published and highly esteemed results that are
discussed in the news should be taken with a large grain of salt. The truth is
that most of the students taking chemistry in high school will not continue a
career in that area, but will nevertheless, as an American taxpayer and
citizen, be expected to make judgments about science. Commercials claim
brilliant scientific advances that will solve the customer's every problem, the
government uses our tax dollars to fund research, arguments about genetic
testing and new drugs are discussed in the news. Students need to be able to
decipher and make sense of the science around them in order to be an informed
citizen and to make wise decisions about their own life. Knowing not to trust
all scientific results and claims is a tool they can use to that end throughout
their lives.
Suggested
activity #1
This
website can be used to convey the concept of the extent of variation in even
advanced scientific research. You will notice that many of the molecules in the
database have multiple entries. Each of these entries has separate data for the
same molecule, from research conducted by different people. Simple exploration
of the database and comparison of molecules will push students to discover that
scientists come up with quite different results even when they are studying the
same molecule using the same method.
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Molecules to explore: