Lesson 2-1

The International System of Measurements (SI)

     In 1960, the Eleventh General Conference on Weights and Measures was held in Paris.  They adopted a universal system of measurement units called Le Systeme International d'Unites (French), which is a revised version of the metric system.  This International System, or SI, as it is commonly referred to, is used for commerce and Science around the world. 

    There are seven SI base units.   Everything that is measurable, can be measured by these base units, or by units derived from these bases.  The table below shows the bases, their international symbols, and what they are used to measure.

Table 2.1a SI Base Units

     Units that are made up of some combination of SI base units are called Derived Units.  Table 2.1b shows some of the derived units that are common in Science.

Table 2.1b Derived Units

 

     Prefixes are used with the base units in order to increase or decrease the value that they represent.  All of the prefixes represent some factor of 10, and they can be used with any of the SI base units.   Table 1.3 represents some of the most common prefixes, their symbols, and the number that is used to multiply the base factor by.

Table 2.1c SI Prefixes

Your teacher can tell you which units and prefixes are most important for the course you are studying.  You must become comfortable with converting units and applying prefixes.  Several practice pages can be found in the links below.

Now, be sure to check out the worksheets and the online quizzes!

Please forward all questions, comments and criticisms to Gregory L. Curran.
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Last Modified February 07, 2008