1. The Metric System
Seventh Grade

2. What is the metric system?
A common system of measurement used throughout most of the world
A decimal system based on powers of 10
Scientists worldwide use the metric system – it is precise
AKA the International System of Units, abbreviated SI

3. What is the metric system?
We use decimals to specify units of measurement when we need more precision
For example, when specifying the height of a person 1.63 meters tall, to say that person is 1 or 2 meters tall doesn’t give us a very good idea how tall that person really is

4. Who invented it? It was first proposed in 1791
The French were the first to adopt it
The National Assembly of France first declared the “new” measures to be the legal measures in France in 1795
Its use in France was made mandatory in 1837

5. Who uses it today? Most of the world All countries EXCEPT:
Myanmar
Liberia
The United States
All industrialized countries except the U.S. uses the metric system

6. The metric system is based on powers of 10
Why? Seems to be a logical choice
Many cultures have used 10 as the basis for their number systems
Probably because humans have 10 fingers and 10 toes

7. Basic Units
Length - the meter
Volume – the liter
Mass – the gram

8. Prefixes: Metric units small than 1 have Latin Prefixes:
Deci = tenth = .1
Centi = hundredth = .01
Milli = thousandth = .001

9. Prefixes: Metric units larger than 1 have Greek prefixes:
Deka = ten = 10
hecto = hundred = 100
Kilo = thousand = 1,000

10. Focus on length: Length = the distance between two fixed points.
The standard unit of length in the metric system is the meter.
A meter is a little longer than a yard.

11. The meter
Scientists spent years carefully measuring two points on Earth at sea level
They used these points to determine the distance from the north pole to the equator – ¼ the circumference of the Earth
They then divided that distance into 10 million parts – each part called a meter

12. Other units of length: Millimeter = mm = .001 meter
Centimeter = cm = .01 meter
Decimeter = dm = .1 meter
Meter = m = 1 meter
Dekameter = dk = 10 meters
Hectometer = hm = 100 meters
Kilometer = km = 1,000 meters

13. Focus on mass Mass = the amount of matter in an object
The standard unit of mass in the metric system is the kilogram
A gram has about the same mass as a paper clip

14. The gram
Scientists tried to establish a unit that would describe how much an object weighs
Because water is readily available all over the world, they decided to call the weight of one cubic centimeter of pure water at a given temperature a gram

15. The gram However, weight is an intrinsically unreliable measurement
Weight is dependent on gravity
A more reliable measurement is that of mass – how much matter an object contains
The kilogram became the standard unit of mass around the world

16. Other units of mass Milligram = mg = .001 gram
Centigram = cg = .01 gram
Decigram = dg = .1 gram
Gram = g = 1 gram
Kilogram = kg = 1,000 grams

17. Focus on volume Volume = the amount of space an object takes up
The standard unit of volume in the metric system is the liter
One liter is a little larger than a quart

18. Other units of volume: Milliliter = ml = .001 liter
Centiliter = cl = .01 liter
Deciliter = dl = .1 liter
Liter = L = 1 liter
Kiloliter = kl = 1,000 liters

19. Focus on time Time = interval or duration elapsing between events
The standard unit of time in the metric system is the second
Metric representation of second = s

20. Other units of time 1 minute = 60 seconds
1 hour = 60 minutes = 3,600 seconds
1 day = 24 hours
1 week = 7 days
1 year = 365 ¼ days (amount of time it takes the Earth to travel around the sun)

21. Other units of time
In practice, every three calendar years will have 365 days, and every fourth year is a “leap year”, which has 366 days, to make up for the extra quarter day over four years. The years 2008, 2012, and 2016 will be leap years. This gives us a total of 52 complete 7 day weeks in each calendar year, with 1 day left over (or two in a leap year).

22. Other units of time
The year is divided into 12 months, each of which has 30 or 31 days, except for February, which has 28 days (or 29 days in a leap year)!

23. Focus on temperature Temperature = the measure of hotness or coldness
The standard unit of temperature in the metric system is degrees Celsius
Metric representation of temperature = °C

24. Focus on temperature
Temperature is expressed in degrees Celsius in the metric system
Water freezes at 0°C
Water boils at 100°C
A hot day is about 30°C
Normal body temperature is 37°C

25. Metric System vs. English
1 meter = 1 yardstick plus the length of a piece of chalk
1 centimeter = the width of some part of your smallest finger or fingernail
1 kilometer = a little more than ½ a mile
1 kilogram = about the mass of 2.2 lbs. of butter

26. Metric System vs. English
1 gram = about the mass of a large thumbtack ( a nickel = about 5 grams)
1 liter = 1 quart plus ¼ cup
1 milliliter = 1/5 tsp. (1 tsp. = 5 ml)

27. The end…
Happy metricating!