1. Unit Conversion and the Metric System
Bio Sciences: Measurements
Unit Conversion and the Metric System
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2. Objectives
List three (3) common measurement systems used in high schools
List common unit conversion equivalencies
Use dimensional analysis to convert between units
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3. Terminology
Unit of Measurement: A definite size of some physical quantity, defined and adopted by convention, that is used as a standard for measurement of the same physical quantity. Dimensional Analysis: A problem-solving method that uses the fact that any number or expression can be multiplied by one without changing its value. Also called the Factor-Label-Method
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4. Units of Measurement
Unit of Measurement: A definite size of some physical quantity, defined and adopted by convention, that is used as a standard for measurement of the same physical quantity.
Basically it is an accepted value that can be converted to other accepted values by simple multiples.
List as many units of measurements as you can in 15sec and be prepared to share!
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5. The key is to use the correct unit in a specific situations
Units Can Represent…
Unit of Measurement can be used to represent
Mass – pounds or kilograms
Volume – gallons or liters
Length – inches or kilometers
Temperature – Fahrenheit or Celsius
Energy – Calories or Joules
Time – Hours or second
Velocity – miles per hour or meters per second
The key is to use the correct unit in a specific situations
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6. Systems of Measurement
There are three (3) systems commonly used if high school science:
The imperial system; in, gal, lbs,˚F, etc.
The metric system; cm, ml, g, ˚C, etc.
The SI system; m, L, kg, K, etc.
We will learn how to convert with in each system and between systems (metric & imperial).
The SI system will be discussed in more detail in your chemistry or physics class.
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7. The Imperial System of Measurements and Conversions
What you are most like familiar with
Length
Unit
Conversion
Equivalence in
feet
12in = 1ft
foot
miles
5280ft =1mile
Volume
Unit
Conversion
Equivalence
Fluid ounce
cups
1fl.oz. =0.125 cup US
cup
quart
1cup US = 0.25qrt US
gallon
1qrt US = 0.25gal US
Mass
Unit
Conversion
Equivalence
ounce
pounds
16oz =1lbs
Temperature
Unit
Fahrenheit (˚F)
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8. The Metric System of Measurements and Conversions
It is a base 10 system – that makes it easy to use, these are the most common metric units we will see.
Measurement
Base Unit
Mass
Gram (g)
Volume
Liter (l)
Length
Meter (m)
Temperate
Celsius (˚C)*
Useful volume relationship
1ml = 1cc (cm3)
Power of 10
103
100
10-1
10-2
10-3
10-6
10-9
Abbreviation k
g, l, m d c m n
Prefix
kilo-
base
deci-
centi-
milli-
micro-
nano-
* Never gets a prefix – does not change magnitude
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9. Some Equivalences Between Systems
Metric
Imperial
Equivalence
Volume
ml or cm3
fl. oz.
1fl. oz. =26.57ml
Mass g oz
1oz =26g
Length cm in
1in = 2.54cm
Temperature ˚C ˚F
˚C to Kelvin (K) NA
K = ˚C+273
This is just a few equivalencies, there are many, many more.
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10. Converting Units of Measurements
Suppose you are given a bottle some chemical and need to weigh out 40mg of it, but your scale only reads out weight in ounces, what do you do? THINK-PAIR-SHARE
You need to convert 40mg to oz., but how?
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11. How many jumps does it take?1 2 3
KILO 1000 Units
HECTO 100 Units
DEKA 10 Units
DECI 0.1 Unit
Meters Liters Grams
CENTI 0.01 Unit
MILLI Unit
How do you use the “ladder” method?
1st – Determine your starting point.
2nd – Count the “jumps” to your ending point.
3rd – Move the decimal the same number of jumps in the same direction.
4 km = _________ m
Starting Point
Ending Point
How many jumps does it take? 4. 1
__. 2
__. 3
__.
= 4000 m

12. Ladder Method King Henry Died By Drinking Chocolate Milk Kilo = x1000
Basic units = Mike Likes Girls
(Meters, Liters, Grams)
How big am I compared to the base unit??
Kilo = x1000
Hecto = x100
Deca = x10
Deci = 1/10
Centi = 1/100
Milli = 1/1000
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13. How to Make Unit Conversions Easy!
The most powerful tool next to your calculator and algebra skills for working with numbers is something calls Dimensional Analysis: A problem-solving method that uses the fact that any number or expression can be multiplied by one without changing its value. Also called the Factor-Label-Method If you get this down the rest of science math is easy
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14. Dimensional Analysis: Basics
ALL order of operations rules apply here and other than that this is the basic format presented.
Numbers chosen so that the
top is equal to the bottom.
Units you want at the end
Units you start with
to cancel out.       =
What you
start with  
What you will get

15. Closure
In your notebook on the left side, write down any struggles you have with the metric system or dimensional analysis.
If you do not have any, then right down some tips or tricks that have helped you understand either one.
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