SI measurement

​How do you measure things?

​Is this method really that accurate?

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Not all bananas are the same size. From the picture, you cannot tell if the beetle is on a large banana or a small banana. The beetle could be on:

• a tiny Ducasse banana;

• a medium Cavendish banana; or

• a large plantain.

The size of the banana affects how large the beetle seems in comparison. Bananas are also impractical to use for measurement because they rot after several days on the counter.

Instead of using random objects to measure, scientists developed standardized units of measurement.

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In today's lesson, you will learn about a system of measurement that all scientists use. You will learn:

• what the SI system is;

• what the prefixes on units in the SI system mean; and

• how to take measurements using the SI system.

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SI Basics

The International System of Units, or SI system, is a system of measurement used by scientists in every country. The SI system is also called the metric system.

​The SI system is standardized. The word standardized means that the measurements are standard, or the same, no matter who takes the measurement. Scientists who speak different languages can still communicate measurements using the SI system.

​The SI system is based on the number 10. You can convert SI measurements to other units by multiplying or dividing by 10. Using a base of 10 makes the SI system simpler than the customary system often used in the United States, which has 12 inches in 1 foot or 3 feet in 1 yard.

​Check out this video on units in the SI system.

​SI system: is an international system of standardized measurement used by scientists worldwide.

​All major industrialized nations have agreed to use the SI system.

Scientists can communicate in a universal scientific language

​Distance = meter
Kilogram = mass
Second = time