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Physical Measurement Laboratory

Office of Weights and Measures

Becoming Familiar with SI

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The SI (metric system) is easy to use! Learn everyday SI reference points

Learning the SI (International System of Units, commonly known as the metric system) requires developing just a few reference points - a general indicator you can use to orient yourself. Reference points help build that innate understanding of "how much." The metric system is a complete measurement system made up of 7 base units. Once you are familiar the SI basics you are ready to go! HINT: Learning the SI is not about making unit conversions in your head (this will only slow you down). Check out these resources to learn to "think metric"...

  • Metric Estimation Game (SP 1336):
    • This game is a fun, hands-on activity that helps participants become familiar with SI measurements by practicing estimation skills. During this activity, participants will become familiar with using the metric system (International System of Units, SI) measurements on common, everyday items.
  • SI Units Card Deck (SP 1297):
    • This interactive educational activity offers a fun way for students to enhance their understanding of the International System of Units (SI), including the Defining Constants, Base Units, Derived Units with Special Names, and Prefixes. With multiple game variations, games may be differentiated for multiple instructional and skill levels.
  • Metric Kitchen:
    • Completing a metric recipe is an opportunity to apply culinary math, expand measurement skills, interpret instructions, complete steps in a necessary sequence, troubleshoot, build self-confidence, and enjoy the delicious results!
  • 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!

How Big are Things Cube (Vendian).

U.S. Temperature Map Celsius (Weather Central).

Explore successive orders of magnitude.

electromagnetic spectrum with the approximate location of the DUV and EUV wavelengths highlighted. DUV wavelengths are about the size of bacteria, whereas EUV wavelengths are closer to the size of molecules.
The electromagnetic spectrum with the approximate location of the DUV and EUV wavelengths highlighted. 
Credit: B. Hayes/NIST

 

Nanotechnology - learn about the very small.

Trimetasphere molecule
Credit: Graphic courtesy LUNA Innovations
10 to the -9 (nano)
Credit: Pixabay

 

Device with nanosoccer fields chip visable through glass window. This images is an interpretative depiction of the magnification of a nanosoccer field.
Credit: Sarah Reeves/NIST Museum

  • Nanotechnology - NIST and Nanosoccer (NIST). Explore how nanosoccer worked and how its lessons helped pave a path toward working microrobots.
  • Bend It Like NIST: Tiny Soccer Players Pave Way for Microrobots (NIST). Imagine a robotic athlete six times smaller than an amoeba playing with a "soccer ball" no wider than a human hair ... with all of the action happening on a field the size of single grain of rice.
  • What is Nanoscale? (University of Wisconsin-Madison). Try out this activity to see how everyday objects compare to the nanoscale.
  • How the Nanoscale Measures Up (National Geographic Society). Hands-on activities help students explore the nanoscale and how it compares to the macro and micro scales.  Incorporate mathematics and visual media.
  • How Small is Nanotechnology? (Lawrence Hall of Science). Explore these activities to learn how scientists measure at the nanoscale.
  • The Micro and Macro Worlds (NNIN) This activity focuses on scale and the importance of using scale bars when presenting nanoscale structures.
  • How Small is Small? (Lawrence Hall of Science). Play a game! Can you arrange these objects from smallest to biggest? Sure, it's fun!

A 10 µm × 1 µm fluorescently labeled rod being controlled to travel along the NIST path

EXPLORE THE METRIC PROGRAM

Unit Conversion | Everyday Estimation | Metrication FAQs | Prefixes | Metric Kitchen | SI Education and Training | SI Publications | SI Basics | SI Teacher Kit | SI Professional Development | Understanding Metric | Writing with Metric Units | National Metric Week | NEST-R (STEM Registry) | NIST Education Resources 

Metrology, Metric and Weights and measures

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Created April 13, 2010, Updated July 15, 2025
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