The Metric System Seventh Grade

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

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

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

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

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

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

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

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

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.

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

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

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

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

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

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

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

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

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

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)

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).

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)!

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

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

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

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)

The end… Happy metricating!