LAB 3
MEASUREMENT
Objective: To become familiar with basic measurements and units used in the sciences.
Measurements allow us to describe things quantitatively. In science, the metric system is the standard for measurements.
One advantage of the metric system is that it is based on units of ten, making conversions from unit to unit easier. This
section of the lab will provide you with a brief overview of some measurements often used in science and the health
professions.
Kilo(k)  Base  Centi (c)  Milli (m)  Micro () Nano (n)  Angstrom (Å)
NO FRACTIONS!
A. LENGTH
B. VOLUME
C. MASS
The metric unit of length is the
meter. Learn the relationships
of the following related units
and make the conversions
indicated. (See Metric System
Table).
The metric unit of volume is the
liter (L), which is slightly more
than a quart.
Mass is the amount of matter in an
object and it is constant. The unit
of mass is the gram. Doses of
medicine are usually milligrams or
micrograms, while body weight is
measured in kilograms.
Approximate Comparisons
(1) 12 oz Soda = 360 mL
Meter (m)
Centimeter (cm)
Millimeter (mm)
Micrometer/micron (m)
Nanometer (nm)
Angstrom (Å)
Make these conversions:
352 cm =
mm
150 km =
m
2000 m =
mm
12 cm =
nm
1 mm =
m
(1) cup of coffee = 180 mL
Make these conversions:
(1) fluid ounce = 30 mL (cc)
A 70 kg man =
(1) teaspoon = 5 mL (cc)
300 g =
mL
5 oz =
mL
5 cups of coffee =
mg
4000 g =
Make these conversions:
1L=
lbs
mg
Mr. Rose weighs 220 lbs. He
receives a dose of medicine at 1
mg/kg body weight. How much
medicine does he receive?
mL
1 L of medicine will make how
many 5 mL injections?
520 g =
4300 g =
mg
g
injections
100 nm =
1Å=
mm
QUESTIONS SIMILAR TO
THESE WILL APPEAR ON
YOUR EXAMS
nm
NOTE:
 When converting to a smaller unit, the number should increase so move the decimal point will to the right.
 When converting to a larger unit, the number will decrease so move the decimal point to the left.
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D. Questions
1.
How many inches equal 1 millimeter? __________________
2.
The prefix kilo means __________________
3.
What instrument would you use to measure fluids in the metric system? __________________
4.
What units would the above measurement be in if it were a small amount of fluid (about a cup)? ____________
5.
What units would the measurement be in if you were measuring a large amount of fluids (a large swimming pool)?
__________________
E. Using Measurements
You can use metric measurements to estimate the size of an object under the microscope. You must begin by measuring
the field of vision on the microscope with a metric ruler.
Example: A metric ruler was placed in the field of vision with the 10X objective in place. The ruler under the field of
vision is shown below:
1.
Assume the marks on the diagram above designate mm. What would the size of the field of vision be on the
diagram above?
2.
Place a metric ruler under each objective lens on your own microscope and measure the fields of view. The space
between each visible line is equal to one millimeter. Record the measurement below:
4X =
10X =
40X =
3.
Now that you have the size of your fields of vision, remove the ruler. You should not have to measure again as long
as you use the same microscope. You can now use this information to estimate the size of an object in the field of
vision. For example:
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3 mm
a.
To find the length of one cell in the field of vision above, you would first visualize and estimate how many cells
would fit across the length of the field of vision. In this case, approximately 6 cells fit across the length of the
field. The length of one cell can be calculated using the following formula:
diameter of field
 size of cell
# cells visible
b.
If you plug in the proper numbers, you will find the answer by calculating:
3 mm
6 cells
c.
The answer is:_________________mm
Now calculate the height of one cell using the same method (show your work):
The answer is:________________mm
4.
Put the prepared slide of the colored strings on your microscope and focus it in on low-power. Use the method you
have just learned to estimate the width of one string (pick one of the colored strings and estimate how many times it
will fit across the field of vision). Do the calculations and show your work below:
The width of the __________ color string is ___________ mm
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F. Questions
___________________
1.
How many millimeters equal an inch?
2.
Estimate the dimensions of a single cell of Elodea in microns ___________________
3.
If 10 cells are visible across the width of the microscope field using the 4X objective lens, and 4 cells are visible
along its length, what are the dimensions of the cell in millimeters?
In microns?
___________________
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___________________