This Catalyst article looks at the changing definition of the kilogram, a unit of mass and a base unit in the SI system (the International System of units).
It has been found that the International Prototype Kilogram (IPK), made in 1879 and kept in a vault in Paris, has lost about 50microgrammes of mass over the years. This may not seem a lot but a new standard kilogram has to be defined. The article can be used to stimulate discussions on topics such as precision, accuracy and the need for standard measurements.
This article is from Catalyst: Secondary Science Review 2012, Volume 22, Issue 3.
Catalyst is a science magazine for students aged 14-19 years. Annual subscriptions to print copies of the magazine can be purchased from Mindsets.
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