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Measurementin Science

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Customary Units vs. Metric Units

DISTANCEInches, Feet, Yards, Miles Meters

LIQUIDSCups,Pints,

Quarts, Gallons Liters

WEIGHT/ MASSOunces, Pounds,Tons Grams

TEMPERATURE

° Fahrenheit ° Celsius

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What is a standard?It is an exact quantity that people agree to use for comparison.

Why are measurement standards important?A meter in the U.S. is the same as a meter in France.

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SI Units are...

International International StandardsStandards

Abbreviated SI from the French Le Systeme Internationale d’Unites or the

Common Name of the Metric System

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Can you think about any situations that we use the Metric System in our everyday life – either home or at school?Name at least 3 examples:1.2.3.

Come on

brain!!

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Pros & Cons of Metric System

• Pro’s– Easy: based on

the use of ten– Conversions are

easier - Just move decimal point

– Used all over the world – not just USA

• Con’s– History of conflict

all over the world– People don’t want

to change– Replacement cost

of machinery to high

Why should we use this system?

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Prefix Symbol Factor Number Factor Word Kilo k- 1,000 Thousand

Hecto h- 100 Hundred Deka da- 10 Ten BASE m, l, g 1 One Deci d- 0.1 Tenth Centi c- 0.01 Hundredth Milli m- 0.001 Thousandth

International Standard Units (SI)

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centi- meter

milli- liter

kilo-gram

(0.01)

(.001)

(1000)

Putting It All Together

hundredth of a meter

thousandth of a liter

thousand grams

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From LARGEST to smallest the easiest way to remember the prefixes is in a sentence……..

King Henry dances merrily down center main.Or..

King Henry doesn’t milk dairy cows on Mondays.

Kilo- Hecto- Deka- BASE deci- centi-milli-

Meter, Liter, Grams

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Metric Conversions

Kilo- Hecto- Deka- BASE deci- centi-milli-

Step 1: Locate the DECIMAL POINT in the number that you need to convert.

27.025 g = _________ cg

Step 2: Mark the starting point (where the decimal point is in the original number) on the guide.

Decimal Point

.

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Step 3: Mark the ending point (where the decimal point is in the final number) on the guide with an X.

.Kilo- Hecto- Deka- BASE deci- centi-milli- X

27.025 g = _________ cg

This is the direction the

DECIMAL will move.

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Step 4: Move the decimal point (.) in the direction of the X. Stop moving the decimal when you reach the X. That’s how many places you need to move the decimal point in the original number.

1 2.Kilo- Hecto- Deka- BASE deci- centi-

milli- X

27.025 g = _________ cg

2702.5

27.025 g = _________ cg

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SI Units for Measurement Used in ScienceLength / Distance

Volume

Measured in meters (m)

Irregular Shape – Displacement MethodFinal Reading – Initial Reading = VolumeMeasured in milliliters (mL)Example: Liquids, rocks, marbles

Metric ruler:

Graduated cylinder:

Regular Shape – Length X Width X HeightMeasured in cm3

Example: box, land, table topsMetric ruler:

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Continued - SI Units for Measurement Used in Science

TimeMeasured in seconds (s)

Clock:

Temperature

Measured in degrees Celsius (OC)

Thermometer:

MassMeasured in grams (g)

Balance:

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……the amount of mass in a given the amount of mass in a given volumevolume

Formula to calculate Density:Formula to calculate Density:

Units are expressed as:Units are expressed as: - g/mL – density of a liquid- g/mL – density of a liquid - g/cm- g/cm33 – density of a solid – density of a solid

MassMassVolumeVolume

Density =Density =

DD

MM

VV

DensityDensity

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When measuring an object with a ruler, never start at the “0” mark.

Rulers are less accurate due to wear and tearwear and tear at the ends.

Begin at the 2, 4, 5 or 6 cm mark in order to get the most accurate mark.

Using a Ruler

The red line would be 1.2 cm1.2 cm because the “5” is the starting point.

What is the length of the red line? 6.2 cm or 1.2 cm

6.2 – 5 cm = 1.2 cm

5 6

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Reading the Meniscus

When measuring liquid volume in a graduated cylinder, a meniscus often forms where the liquid ends.

graduated cylinders

In order to read this liquid volume, you must be at “eye-level” to the level of the liquid.

You take the reading at the BOTTOMBOTTOM of the meniscus.The liquid level is 36.5 mL.

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Read these liquid volumes in mL:

11.5 mL76.0 mL

A. B.