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Measurement League: Guardians of the SI Superhero Card Set

Black and White graphic.  Left side has black images of scales, rulers, SI logo.  Right side has white images on black background of same items.  The middle of image has a gray cirle with EDUCATION in black letters.


Keywords:SI, superhero, metric, mass, kilogram, length, meter, temperature, time, second, mole, ampere, electric current, kelvin, candela, brightness, uncertainty, error
Audience:Students, Parents, Educators, General Public, Technology Coordinators, Outreach Ambassadors
Grade Level: 3 to 5
Subjects:STEM, mathematics, physical science, chemistry, engineering




SI Superhero Card Set
Edition: 2021

Collage of Guardians of SI Superheroes
Credit: NIST


This digital resource feature profiles for each of the Measurement League: Guardians of the SI superheroes, dedicated to the fight against uncertainty, imprecision, and inaccuracy and to improving the quality of our lives and the things we build. The superheroes include the following: Mole, Professor Second, Monsieur Kilogram, Ms. Ampere, Dr. Kelvin, Meter Man, and Candela. Each card in the set lists a different superhero’s name, picture, symbol, and the measurement unit they represent. The card set provides an entertaining way to learn more about the International System of Units (SI).

Learning Objectives

  • Describe the 7 SI base units
  • Recognize unit definitions


  • Digital file


If printed, use caution when handling paper edges and scissors to prevent injury.

Teaching Tips

Explain the SI base units, unit definitions, and metric prefixes. State each base unit depends upon a defining constant. Additionally, mention the combination of SI base units creates the SI derived units. Single hardcopy set is available while supplies last. Contact the NIST Metric Program at TheSI [at] (TheSI[at]nist[dot]gov) and include your name and U.S. mailing address.

Classroom Connections

Additional Resources


Created July 13, 2022, Updated February 13, 2024