Subject: meters

I am a 7th grade student and need to find the answer to this question. The length of a meter has been determined in three different ways. The first and original way was determined in 1798. The second way was determined in 1960. The third and current way was determined in 1983. What were the three ways and why were the first two abandoned? Thank you,
Jarod Fischer

Hi Jarod,

I did a sreach and found some links that may help

A chronology of the SI metric system

National Institute of Standards and Technology - talks about history of units.

Historical context of the SI

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