The metric system, often referred to as SI (System Internationale), is a decimal system with units that are logically related; it is widely used around the world, and in science and manufacturing.
Basic Units
- gram – (mass/weight) originally, the weight of a cube of water holding 1/100 meter or 1 cubic centimeter (cm3), or about 1/28 ounce (1 ounce = about 28.35 grams)
kilogram = 1,000 grams, or approximately 2.2 pounds - liter | litre – (volume) = 1,000 cubic centimeters (cm3), or approximately 1.75 pints
- meter | metre – length , or approximately 39.37 inches (originally based on the length of a pendulum with a period of 1 second)
Other common base units:
- are – 100 square meters (1/100 of a square kilometer)
hectare = 10,000 square meters, or about 2.47 acres - degree (°) – temperature using Celsius / centigrade scale. 1°C=1.8°F; the zero point for the Celsius system is the freezing point of water, or 32°F
[°C = °F -32 * 5/9; °F = °C * 9/5 + 32] - joule (J) – energy (107 erg)
- Newton (N) – force
- Pascal (Pa) – pressure
- quad – 1015 Btu
- second – time
- Watt
– power (amperes * volts)
In the metric system, larger and smaller units are designated by prefixes; here are some of the most common:
- pico (p)– 1 trillionth, 10–12
- nano (n)– 1 billionth, 10–9
- micro (µ) – 1 millionth, 10–6
- milli (m) – 1 thousandth, 10–3
- centi (c) – 1 hundredth, 10–2
- deci (d) – 1 tenth, 10–1
—
- deca (da) – ten (101)
- hector (h) – 100 (102)
- kilo (k) – 1,000 (103)
- mega (M) – million (106)
- giga (G) – billion (109)
- tera (T) – trillion (1012)
You can obtain a free set of metric education resources for use in your classroom! Contact the NIST Metric Program at TheSI@nist.gov and include your name, school, subject, grade level, phone number, and mailing address. The NIST SI Teacher Kit contains a classroom set of metric rulers (NIST SP 376 – a 300 mm ruler), laminated metric conversion cards (NIST SP 365), SI Education CD, and other measurement resources.
Additional Resources on the Metric System
- Education Resources on the Metric System (SI). National Institute of Standards & Technology website. [www.nist.gov/pml/weights-and-measures/education-resources-metric-system-si]
- Math Is Fun – Metric System of Measurement. Math is Fun website. [www.mathsisfun.com/measure/metric-system.html]
- Metric Bookmark [PDF]. National Institute of Standards & Technology website. Master sheet for printing metric system bookmarks for students. [www.nist.gov/sites/default/files/documents/pml/wmd/metric/bookmark.pdf]
- Metric Chocolate Chip Cookies. National Institute of Standards & Technology website. [www.nist.gov/pml/weights-and-measures/metric-chocolate-chip-cookies]
- Metric Recipes and Recipe Conversion. The Metric Kitchen website. [www.jsward.com/cooking]
- The Metric System, the U.S.A., and Scientific Literacy. Public Library of Science website. [blogs.plos.org/scied/2013/01/28/the-metric-system-united-states-of-america-and-scientific-literacy]
- Everyday Use of Metric. Think Metric website. Created for the U.K., but has useful information. [thinkmetric.org.uk/everyday.html]
- Every Day With Metric. National Institute of Standards & Technology website. [www.nist.gov/pml/weights-and-measures/metric-si/everyday-metric]
- SI Teacher Kits for Educators. National Institute of Standards & Technology website. [www.nist.gov/pml/weights-and-measures/si-teacher-kits-available-educators]
Also see Resources that apply to many subject areas and Readings for students.
