DO NOW 1.How are SI units of measurement different from other units of measurement we use in the US (such as feet, gallon, miles, pounds etc.)? 2.What are the SI units of measurement for: a.Length b.Volume c.Mass d.Time e.Temperature 3. What tools or devices are used to make measurements: a.Length b.Volume c.Mass d.Time e.Temperature

 SI system uses prefixes so scientists do not have to write a lot of decimal places and zeros For example, compare: Thickness of a strand of hair:.00009m Thickness of a page:.0001m Distance from your house to your friend’s house: 20 meters Distance from here to China: 11,000,000 meters  Scientists convert, or change, SI units to smaller or larger units using factors (or ratios) Taking a step back… Let’s focus on these two concepts for the rest of the period…

Using prefixes in measurements  Prefixes hold places of decimals and zeros Example, the prefix kilo- holds the place of three 0’s in 1000 base units 1 kilometer = 1000 meters The prefix centi- holds two places after the decimal point in.01 base units 1 centimeter =.01 meter

The prefixes are… kilo- hecto - deca- [base unit] deci- centi- milli- Larger Smaller Symbols for the prefixes are: k- h- da- [b. u. abbv.] d- c- m- When writing measurements, the first letter stands for the prefix, the second letter stands for the unit of measure Example, kL = kiloliter, mm = millimeter

Let’s practice!!!! Write out the units of measurement for the following: Ex. mm = millimeter 1) mL 2) dag 3) dL 4) hm 5) dg 6) hL 7) kg Abbreviate the following units of measurements: Example: cm = centimeter 1) hectometer 2) decagram 3)milliliter 4) decigram 5) kilometer 6) centimeter

FACTORS OF 10 SymbolPrefix Multiples of base unit Example m-milli millimeter =.001 meter c-centi centimeter =.01 meter d-deci-.1 1 decimeter =.1 meter -(base unit)1 meter da-deca-10 1 decameter= 10 meter h-hecto hectometer = 100 meter k-kilo kilometer = 1000 meter

CONVERTING between units. 1. Moving decimal places: Example: convert 275 kg to ____g kilo- hecto - deca- [base unit] deci- centi- milli- Moved three prefixes to the right from kilogram to grams, move three decimal places to the right kg = g

Let’s Practice! Moving decimals! kilo- hecto - deca- [base unit] deci- centi- milli- Covert the following units as indicated: 1) 232m = 2.32 hm 2) 4.24 km = 4240 m 3).039m = 39 mm 4) 923 dam = 9230 m 5) 2.3m = 230 cm 6) 239 dm = 23.9 m

CONVERTING between units 2. Using conversion factors: GIVEN x CONVERSION FACTOR = UNKNOWN Conversion factors are determined using relationship between the units involved. Example: 1 millimeter =.001 meter Conversion factors are the ratios of the units involved Example: 1millimeter.001meter.001meter 1 millimeter

CONVERTING between units 2. Using conversion factors: GIVEN x CONVERSION FACTOR = UNKNOWN Example: 3.89 dag = 38.0 g Relationship between units: 1 dag = 10 g