1. Why do we need to be able to measure things?
To make sense, all measurements need both . . .
Why do we need to be able to measure things?
Suppose we wanted to measure a 2 x 4 for building a house.
Units by themselves don’t make sense.
Numbers by themselves don’t make sense.
A Number
and
a Unit!
A board is meters long
A board is 350 long
Any Ideas?

2. Precision and Accuracy
Precision is a description of how close measurements are to each other.
Accuracy is comparing your measurement to the actual or accepted value.

3. Basic Types of Measurement
Length: measures distance between objects
Volume: measures the amount of space something takes up
Mass: measures the amount of matter in an object
Other Types of measurement include:
time
temperature
density PH

4. Measurement System Comparisons
ENGLISH
SI SYSTEM
LENGTH
Yard / Inch
Meter / Centimeter
MASS
Ounce / Pound
Gram / Kilogram
VOLUME
Quart
Liter
TEMPERATURE
Fahrenheit
Celsius / Kelvin
TIME
Second
All Measurement systems have standards. Standards are exact quantities that everyone agrees to use as a basis of comparison.

5. The SI System uses the following prefixes:
Kilo
1000
Hecto
100
Deca 10
UNIT 1
Deci
1/10
Centi
1/100
Milli
1/1000
This system works with any
SI measurement.
The UNIT becomes whichever type of measurement you are making. (mass, volume, or length)
It is the same system regardless if you are measuring length, mass, or volume.

6. centi gram It works for all types of measurement.
If you’re measuring . . .
Length then it is the meter (kilometer, decameter, etc.)
Mass then it is the gram (centigram, milligram, etc.)
Volume then it is the liter (deciliter, hectoliter, etc.)
centi
gram
The first part of the term indicates the amount, the second part indicates the type of measurement.

7. How does converting units work?
Unlike the English system converting in the SI System is very easy. For Example in the English system if you wanted to know how many inches in 2 miles what would you do?
Take the number of miles (2).
Multiply it by the number of feet in a mile (5,280).
Multiply that by the number of inches in a foot (12).
ANSWER: 126,720 inches in 2 miles

8. The SI system is much easier.
For example in the metric system if you wanted to know how many centimeters were in 3 meters, what would you do?
Find the unit you have (meters).
Find the unit you are changing to (centimeters).
Count the number of units in-between (2).
Move the decimal point that many spaces, in the same direction you counted (right).
3 meters =
300 centimeters
Kilo Hecto Deca UNIT Deci Centi Milli

9. Kilo Hecto Deca UNIT Deci Centi Milli
More Conversions . . .
2,321.0 millimeters to meters
= meters
521.0 grams to hectograms
= hectograms
NOTE: The digits aren’t changing, the position of the decimal is. In the English system the whole number changes.
Kilo Hecto Deca UNIT Deci Centi Milli

10. Things to Remember All measurements need a number and a unit!
Basic units of Measurement (meter, liter, gram)
How to convert metric units

11. Basic Types of Measurement
Length: measures distance between objects
Volume: measures the amount of space something takes up
Mass: measures the amount of matter in an object
In SI the basic units are:
Length is the meter
Mass is the gram
Volume is the liter (liquid)
Temperature is Celsius

12. Measurement Review Measurements need a number and a unit!
Basic units of Measurement (meter, liter, gram)
How to convert metric units
Be able to make basic measurements of volume, length, and mass
Vocabulary words

13. Conversion Factors
Fractions in which the numerator and denominator are EQUAL quantities expressed in different units
Example: in. = 2.54 cm
Factors: 1 in and cm
2.54 cm in.

14. Conversion factor 2.5 hr x 60 min = 150 min 1 hr cancel
How many minutes are in 2.5 hours?
Conversion factor
2.5 hr x min = min
1 hr
cancel
By using dimensional analysis / factor-label method, the UNITS ensure that you have the conversion right side up, and the UNITS are calculated as well as the numbers!

15. = 29 quarters Sample Problem
You have $7.25 in your pocket in quarters. How many quarters do you have?
7.25 dollars quarters
1 dollar
= 29 quarters X

16. A rattlesnake is 2.44 m long. How long is the snake in cm?
a) cm
b) 244 cm
c) 24.4 cm

17. Kilo Hecto Deca UNIT Deci Centi Milli
Solution
A rattlesnake is 2.44 m long. How long is the snake in cm?
b) 244 cm
Kilo Hecto Deca UNIT Deci Centi Milli

18. Amount of People in the World.
There are 6,900,000,000 people in the world.
What is a better way to write this HUGE value?
Scientific Notation
6.9 X 109 People
Why are we able to write the number like this?

19. Significant Figures – long story short, this is how well you measured something.
The most confusing parts are the zeros
Rules

20. Decimal ‹ 1 – start from left, count all nonzero + zero between
No decimal – trailing 0 – not sig.
Ex: sig. figs
- zeros between nonzero are
sig.
Ex: sig. figs
Decimal ‹ 1 – start from left, count all nonzero + zero between
Ex: sig. figs.
Ex: sig. figs
Decimal › 1 – all count
Ex: sig. figs

21. How many significant figures are in the following:
203.4
7600

22. How many significant figures are in the following:
Decimal › 1 – all count
No decimal – trailing 0 – not sig.
- zeros between nonzero are sig.
Decimal ‹ 1 – start from left, count all nonzero +
zero between