The International System of Units (SI), commonly known as the metric system, is the international standard for measurement. SI use in product design, manufacturing, marketing, and labeling is essential for United States industry's success in the global marketplace. SI measurement system familiarity and fluency must be developed along the Science, Technology, Engineering, and Mathematics (STEM) career pipeline to produce an U.S. engineering workforce with this essential 21st century skill.
- NIST Metric Trivia Quiz – How much do you know about the metric system (SI)? Try the NIST Metric Trivia Quiz online or use the Alexa skill to test your knowledge and be on your way to thinking metric!
- SI Basics – Learn more about the 7 base units that define 22 derived units with special names and symbols
- SI Teacher Kits Available for Educators – Obtain a free set of metric education resources for your classroom
- Education Resources on the Metric System (SI) – A collection of resources to enrich classroom curriculum and reinforce student learning
- Occupational Metric System Training – A workbook series containing educational information that apply metric measurements within a variety of occupations
- Writing with SI (Metric) Units – Find quick answers to SI questions that arise while writing and reviewing technical documents
- Presidents and Measurements – Measurement education resources celebrating Presidents’ Day national holiday
Teaching the New SI
In November 2018, the world’s measurement experts voted and unanimously approved a revision of the SI that establishes a measurement system entirely based on physical constants of nature. The changes took effect on World Metrology Day, May 20, 2019. Learn more about the Road to the Revised SI.
- An Introduction to the New SI, Physics Teacher, 55, 1, 16-21. Knotts, S., Mohr, P. J., & Phillips, W. D. (January 01, 2017) - DOI: 10.1119/1.4972491
The brief, six-page article is designed to be a resource for teachers who are introducing the International System of Units (SI) into their classrooms and helping students realize the importance of the new changes. The proposed revision (if approved in November 2018) will for the first time define all seven (7) SI base units in terms of fundamental constants.
- A More Fundamental International System of Units, Physics Today 67, 7, 35. Newell, D. (July 1, 2014)
- Operating Principles of the NIST 4 Watt Balance Source (Video)
The watt balance lets researchers determine the mass of an object indirectly by determining two quantities: the strength of the magnetic field, and the current running through a coil of wire.
- The NIST Do-It-Yourself Kibble Balance (Made with LEGO® Bricks!)
The NIST "D.I.Y." Kibble balance is a science project that teaches the principles used in the international kilogram redefinition effort. Students, teachers and science enthusiasts can build a working demo Kibble balance capable of performing mass measurements with as little as 1 % uncertainty, making them more accurate than some commercial jewelry, cooking, and postage scales.
- NIST in 90: Measuring Planck's Constant (Video)
The Measurement League: Guardians of the SI
The Measurement League: Guardians of the SI are superheroes dedicated to the fight against uncertainty, imprecision, and inaccuracy and to improving the quality of our lives and the things we build, using their incredible powers of measurement to perform amazing feats of science and engineering. This comic book-style video animation series has been developed to help middle school students learn about the 7 SI base measurement units. Videos are available on the NIST YouTube Channel.
Episode 1: Desperate Measures!
The SI Superheroes use the power of measurement to help a stranded soccer player get home.
Episode 2: Running Out of Time!
The SI Superheroes battle archvillain Major Uncertainty in a race to keep the world's satellite navigation system "on time."
Episode 3: Mass Hysteria!
The nefarious Major Uncertainty has kidnapped Monsieur Kilogram, putting the world’s measurements of mass in jeopardy.
SI Superhero Card Set (PDF) - Download a printable version of the Superhero Cards. Each card in this set lists a different superhero’s name, picture, symbol, and the measurement unit represented. A short description of the superhero’s powers are on the back of each card.
SI Measurement System Chart - SP 304A (2017) - This publication is a colorful chart explaining the 7 base units of the SI, prefix symbols, and features the Measurement League: Guardians of the SI. Submit hard copy requests to TheSI@nist.gov or print a copy (select “print to fit”). Original dimensions: 279 mm by 432 mm (11 in by 17 in).