How Do Scientists
Measure?
The Metric System
AKA SI or
Système International
Textbook Page 23
Way Back When

When people first started to measure things, the systems were
different in different parts of the world

Many systems were based on parts of the body

Foot
inch
Comparing the two

England started the English Standard (Imperial) System

France started the Metric System

VS
Today…

As of the late 1970s, only the United States, Liberia (Africa), and
Myanmar (formally Burma in Asia) use the English Standard System

Every other country, and scientists worldwide, use the metric system
English Standard System

Based on : 2, 3, 4, 8, 16

Generally uses fractions ex:

2 pints in a quart

3 feet in a yard

4 quarts in a gallon

12 inches in a foot

16 ounces in a pound
Why the Metric System?
 Over
95% of the world uses the Metric
System
 The
metric or SI (scientific international)
system is aids scientists in sharing
measurements
 No
need to convert another person’s data if we
all work in SI
Metric System
 Units
can be scaled by factors of 10
depending on what you are measuring
 So
it can be used for small stuff as well as
large
Units of Measurement

Kilo-
Hecto-
Deca-
1000
100
10
Base- Deci- Centi1
Milli-
1/10th 1/100th 1/1000th
***You are only responsible for the units in black***
Mass

Measurement: mass

Unit used: gram (g)

Tool used: balance

A paper clip has the mass of about 1 gram
Length/Distance

Measurement: length/distance

Unit used: meter

Tool used: ruler/meter stick

A centimeter is about the width of a pinkie
fingernail
Volume

Measurement: volume

Unit used: liter (l)

Tool used: graduated cylinder

A liter is just a little bit more than 1 quart (or 2
pints) of milk
Volume: How to use a graduated
cylinder

When reading a volume ALWAYS read at the
bottom of the meniscus
 Meniscus:
curve in a liquid at the top of a container
due to surface tension
The volume of this liquid is 66 ml
Temperature

Measurement: temperature

Unit used: Celsius (C)

Tool used: thermometer

0 Celsius= freezing point of water

100 Celsius= boiling point of water
Why should we all use the same system?

NASA still works in imperial (English) units and has had difficulty
when needing to work with other groups that use metric

In 1999 the Mars Climate Orbiter was lost because the altitude control
system used imperial units and the navigation software used metric
Metric System

Helpful conversions
 100
centimeters in a meter
 1000
grams in a kilogram
 1000
milliliters in a liter