The SI System of The SI System of Measurement.Measurement.

andandHow to measure LENGTH.How to measure LENGTH.

The Metric systemThe Metric system• Developed in the late 1700’s• Based on multiples of 10• First adopted by the French

in 1793• Adopted by the US Congress

in 1866

SI SystemSI System• SI = “Systeme International d’Unites”• It is an improved version of the

Metric System.• Adopted by the US Congress in

1960.• It is the standard system of

measurement WORLDWIDE!

Base UnitsBase Units• Length = meter • Mass = gram (standard is a

Kilogram)• Volume = liter• Time = second• Temperature = Kelvin• Electric Current = Ampere• Quantity of Matter = Mole

PrefixesPrefixes• milli = 1/1000 (m + Base Unit)(m + Base Unit)• centi = 1/100 (c + Base Unit)(c + Base Unit)• deci = 1/10 (d + Base Unit)(d + Base Unit)• Deka = 10 (da + Base Unit)(da + Base Unit)• Hecto = 100 (h + Base Unit)(h + Base Unit)• Kilo = 1000 (k + Base Unit)(k + Base Unit)

• Every Space is divided into 10 equal parts– One meter is equal to 10 decimeters– One decimeter is equal to 10 centimeters– One centimeter is equal to 10 millimeters– One millimeter is also divided into 10 sections

even though they are not drawn on a meter stick. (This is your Best Guess Number)

How to measure LengthHow to measure Length

ExampleExample

0 1 2 3 4

centimeters millimeters

• How many cm?

• 4.00 cm

# of cm after Zero

# of mm after 4cmBest Guess Number from 1-10 after mm

•How many mm?

•40.0 mm

ExampleExample

0 1 2 3 4

• How many cm?

• 2.40 cm

• How many mm?

• 24.0 mm

ExampleExample

74 75 76 77 78

• How many cm?

• 75.45 cm

• How many mm?

• 754.5 mm

ExampleExample• How many cm?

• 0.23 cm

• How many mm?

• 2.3 mm

0 5

0 5

ExampleExample• How many cm?

• 3.05 cm

• How many mm?

• 30.5 mm