For the Teacher

Guide students to complete the reading passage and 10 questions within 18 minutes.

Check answers by reviewing exact text evidence and reasoning provided in each question block.

For the Learner

Skim paragraphs A–D to understand the main chronological steps before opening the questions.

Answer each question, then compare your work with the detailed evidence breakdown.

A

The French national metrology laboratory says that a French law of 7 April 1795 introduced the decimal metric system. NIST, the national standards institute of the United States, says that in 1791 French scientists proposed to define the metre as one ten-millionth of the distance from the North Pole to the equator, along a line through Paris. In 1799, the French made platinum standards of the metre and the kilogram and put them in the national archives.

B

The BIPM, the International Bureau of Weights and Measures, says that on 20 May 1875 a group of states signed the Metre Convention. The French laboratory says that the group had 17 states. The treaty aimed to unify and improve the metric system around the world, and it also created the BIPM.

C

NIST says that since 1983 the metre has been the length that light travels in a vacuum in 1/299,792,458 of a second. For many years, a small cylinder of platinum and iridium, kept in a vault near Paris, set the size of the kilogram. NIST says that a new definition of the kilogram took effect on 20 May 2019, and the BIPM says that it is based on the Planck constant.

D

The writer's own cautious view, hedged ("I think", "it seems"): I think these dates show that the metric system grew in steps, and it seems that the main units moved from objects to the laws of nature. The sources describe only the metre and the kilogram, so I do not think they show how people in everyday life changed to metric units, and the dates come from several different bodies.

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____ A. As a fraction of the platinum cylinder standard kept in the national archives. ____ B. As a fraction of the distance from the North Pole to the equator along a meridian through Paris. ____ C. As the speed of light traveling through a vacuum in a tiny fraction of a second. ____ D. As a universal decimal measurement ratified by seventeen independent states.

____ A. Everyday adoption occurred immediately upon passing the 1795 legislation. ____ B. The metric system developed progressively in gradual stages rather than all at once. ____ C. The physical platinum cylinders remain the most reliable scientific reference today. ____ D. All standard definitions were established simultaneously by a single central agency.

____ Paragraph A ____ Paragraph B ____ Paragraph C ____ Paragraph D

____ Paragraph A ____ Paragraph B ____ Paragraph C ____ Paragraph D