Tuesday, September 18, 2012

measurement and uncertainty

I am grading labs right now and reflecting on the importance of not only reporting a measurement with the correct units but also including the correct number of significant digits. This is critically important in science. The more I teach this class the more I emphasize its importance. It is the number one reason people get marked down on their lab reports.

I read somewhere recently that there was a major error made by NASA as a result of someone using metric measurements as if they were English measurements. Can you imagine such an error being made by scientists at the level of NASA engineers? I certainly can't. Obviously their introductory chemistry instructors did not emphasize the importance of this critical skill and they were able to mask their ignorance in upper level classes. This resulted in a major problem with a NASA satellite up in space.

At the level of the earthlings, however, the individual errors result in nothing more than a lower grade on a test or lab report. Insignificant in itself, however, predictive of larger problems down the road.

Uncertainty is critical in chemistry. Measurements must be precise and accurate.

1 comment:

  1. You can't imagine how difficult it is to convince students that what I teach about reporting data MUST be implemented in their weekly lab classes when reporting burette readings.... it goes either 9 mL or 9.000 mL when our burettes have 10 sub divisions for each mL.

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