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Classroom-Ready: NIST Releases Updated Metric Ruler and Conversion Card

The NIST Metric Program provides a wide range of educational materials to help students learn to apply the International System of Units (SI), commonly known as the metric system. Two popular resources have been updated and are now available.

Many classroom activities and science fair projects use linear measurements. Expand your classroom toolbox to include the NIST SP 376, Metric Ruler, designed for kindergarten to 12th grade educators teaching SI length. The updated design includes approximate scales of 300 mm and 30 cm. One edge is graduated in centimeters by alternating solid markings in the style of a forensic photo scale. One edge is divided into 1 dm, 10 cm, and 100 mm sections.

: This metric ruler, NIST SP 376 (front), includes approximate scales and is intended to be used as an educational tool for length measurements using the International System of Units (SI).
NIST Metric Ruler Card (SP 376).
Credit: NIST

Unit conversion is a multi-step process that involves multiplication or division by a numerical factor, selection of the correct number of significant digits, and rounding. The NIST SP 365, Metric Conversion Card is a laminated wallet-size card that includes an 8 cm and 80 mm ruler with approximate unit conversion factors between common SI and non-SI (U.S. customary) measurement units for length, area, massvolume, and temperature. This job aid is useful for making quick, approximate, mathematical unit conversion calculations. For example, identify the numerical value of the units in the When You Know column then multiply by the approximate unit conversion factor found in the Multiply By column to obtain a numerical value for the units listed in the To Find Column (e.g., 20 yd x 0.91 is equal to about 18.2 m). Additional unit conversion process guidance, within or between measurement systems, is also available in NIST SP 811, The NIST Guide for the use of the International System of Units (SI), Appendix B.

NIST unit conversion card ruler measures an autumn oak leaf
Use the NIST Metric Conversion Card (SP 365) to measure small objects and perform approximate unit conversions.
Credit: NIST

Access additional metric publications and classroom education resources online. U.S. educators, parents, and outreach ambassadors are encouraged to request the NIST SI Teacher Kit, a curated collection of instructional resources. NIST SI resources are ideal for professional development, training events, laboratory tours, education outreach, metric system training, and management system references. Hardcopy publication requests may be made by contacting the NIST Metric Program at TheSI [at] nist.gov (TheSI[at]nist[dot]gov). Include your name, school, subject, grade level, phone number, and U.S. mailing address.

Released July 7, 2025
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