Teach the New SI

In November 2018, the world’s measurement experts voted and unanimously approved a revision of the International System of Units (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. These resources are intended for students in Grade 6 and above.

SI Units Card Deck (NIST SP 1297)

This fun interactive educational activity is designed to help students enhance their SI understanding, 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. Instructional Level: Grades 3 to Higher Education.

Meet the Constants

The revised SI rests on a foundation of seven values, which are the same everywhere in the universe. These constants define the seven SI base units, from the second to the candela. Engage with the interactive infographic; click on each of the SI units to see which constants define them.

Universal Constants: A New Foundation of Measurement (Jason Learning)

Follow the work of NIST metrologists as they move to measurements based on universal constants. Lessons and activities focus on physical science and mathematics related to the new International System of Units (SI). Explore themes that include redefining measurement, pursuing accuracy, achieving precision, and measurement process innovation. Instructional Level: Grades 8 to 12. Explore Career Role Model Videos for three NIST physicists: Patrick Egan, Darine Haddad, and Toby Herman.

Highlighted Activities:

• Accuracy vs. Precision (Video). NIST Role Models discuss the concepts of accuracy and precision.
• Accuracy vs. Precision - Focus on Precision. Discuss the definitions of accuracy and precision. Compare and contrast between these terms in daily life. Describe the significance of improvements in accuracy and precision.
• Problems with Precision. Explore situations where little variations caused big problems, including the Mars Climate Orbiter and Gimli Glider mix-ups.
• A Planck to Stand On. Learn about the research of Max Planck and explore a simulation.
• Innovating with Constants.  Consider how the move to universal constants supports scientific innovation.
• NIST International System of Units Match Game. Students spin the wheel to select a SI base unit, then select fundamental constants used to form the base unit.

Kibble Balance and LEGO Activities

Credit: Photo illustration by B. Hayes/NIST

• 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.
• A LEGO Watt balance: An apparatus to determine a mass based on the new SI (Instructions).
• How Lego Bricks Shaped My Career at NIST (Article). NIST researcher Leon Chao describes how spending his youth building structures out of Lego bricks translated into professional activities.

Visual Learning Resources

How to Build Your NIST D.I.Y. Watt Balance

NIST in 90: Measuring Planck’s Constant

Operating Principles of the NIST-4 Kibble Balance

Credit: N. Hanacek/NIST

Educational resources

• Relating SI Units to the 'Defining Constants', Metrologia, Blattner, P. and Brown, Richard, J. C. (May 2024) - DOI 10.1088/1681-7575/ad4cef. The direct relationship of any SI unit to the defining constants is discussed.
• An Introduction to the New SI. Physics Teacher, 55, 1, 16 - 21, Knotts, S., Mohr, P. J., and Phillips, W. D. (January 2017) - DOI: 10.1119/1.4972491. This education article highlights recent changes to the seven (7) International System of Units (SI) base units in terms of fundamental constants.
• What Chemistry Teachers Should Know about the Revised International System of Units (Système International), Journal of Chemical Education, 96, 4, 613 - 617. J. Giunta. (January 30, 2019) - DOI: 10.1021/acs.jchemed.8b00707. Approved SI changes that impact classroom chemistry instruction are discussed.
• Introducing High School Students to the Avogadro Number and the Mole Concept Using Discovery with Calculations Based on Physical Properties of Elements, Crystal Structures, and 28Si Spheres, Journal of Chemical Education, 98, 3, 790 - 795. Bindel, T. H. (January 29, 2021) - DOI: 10.1021/acs.jchemed.0c01132. Explore an instructional approach where students discover the Avogadro number and the mole concept.
• A More Fundamental International System of Units, Physics Today 67, 7, 35. Newell, D. (July 1, 2014)

• The Last Artifact documentary (Montana PBS) and companion Grade 5 to 12 educational resources, which document the work that went on behind the scenes to modernize the International System of Units (SI).
• MeASURe Education (University of Cape Town, Department of Physics) classroom materials, including posters, videos, and laboratory guides, are designed to enhance the teaching of measurement and the new SI.

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