What are SI Units?
• Measurement used throughout the world when
performing calculations related to scientific
investigations
• Volume (cm3 =mL)
Choose from: Centimeters, ounce, grams, °C,
milliliters
1.) Which unit of measurement would you use to
record the mass of 10 sunflower seeds?
2.) Which unit of measurement would you use to
record the volume of 10 sunflower seeds?
3.) Which unit of measurement would you use to
record the temperature of a chemical reaction?
4.) Which unit of measurement would you use to
measure the length of 1 sunflower seed.
Why is it important for scientific
measurements to be reproducible and
accurate?
• If you are able to take measurements of an
object and get the same result each time, you
increase your accuracy.
• All experiments should be reproducible. You
should be able to do them again and get the
same exact results
• What does it tell you if you don’t get the same
results the second or third time?
Three important points that you should keep
in mind when you record scientific
measurements
1.) You need both the measurement (for ex: 2.0, 3.4, 5.0) and the
unit (g, mL, s, m) because each scientific measurement has a very
different meaning. *Need to know what you measured
2.) Units need to be apart of an agreed upon system or
measurements would not be accurate
3.) Write the measurement in proper form. This usually means
using a decimal. You want your scientific measurement to be as
accurate as possible.
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1 inch = 2.54 cm
I L = 33.8 fl oz
1000 mm = 1 m
100 cm = 1 m
You need to know SI unit prefixes 
Base scale of 10
kilo x1000
hecto x 100
deca x10
BASE (meter, gram, liter, second)
deci 1/10
centi 1/100
milli 1/1000
For example:
kilometer (1000x more than 1 meter)
hectometer (100 times more than 1 meter)
decameter (10 times more than 1 meter)
meter (1 meter)
decimeter (there are 10 decimeters in 1 meter)
centimeter (there are 100 decimeters in 1 meter)
millimeter (there are 1000 millimeters in 1 meter)
• Density = how much matter is occupying a
certain amount of space
• = the measure of how closely packed matter is
within a given space
• If an object sinks it is DENSER than the liquid it
is placed in
• If an object floats it is LESS dense than the
liquid it is placed in
• Convert 80 °F to °C
• Convert 65 °F to C
• Convert 60 °C to °F
• Convert 20 °C to K
• Convert 55 °C to K
• Convert 100 K to °C