Lab Safety Rules and Symbols
Unit 1, Part 1
Lab Safety
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A few reminders when working in the lab:
– No food or drink in the lab unless I specifically tell you otherwise.
– Always read, re-read, re-re-read instructions, and be sure to ask questions
before you get too far into an experiment.
– Please be mindful of the fact that there will often be close to 30 people in
the lab with you and that your safety and theirs is ALWAYS your first
concern.
– Familiarize yourself with lab equipment, safety symbols, and the location
of first aid materials before beginning an experiment.
Lab Safety Symbols: Glassware Safety
• 1. Whenever you see this symbol, you will know that you are
working with glassware that can easily be broken.
• 2. Never heat glassware that is not thoroughly dry. Never pick
up any glassware unless you are sure it is not hot. If it is hot,
use heat-resistant gloves.
• 3. Always clean glassware thoroughly before putting it away.
Fire Safety
• 1. Whenever you see this symbol, you will know that you are
working with fire. Never use any source of fire without
wearing safety goggles.
• 2. Never heat anything unless instructed to do so.
• 3. Never heat anything in a closed container.
• 4. Never reach across a flame.
• 5. Always use a clamp, tongs, or heat-resistant gloves to
handle hot objects.
• 6. Always maintain a clean work area, particularly when using
a flame.
Chemical Safety
• 1. Whenever you see this symbol, you will know that you
are working with chemicals that could be hazardous.
• 2. Never smell any chemical directly from its container.
Waft instead.
• 3. Never mix chemicals unless instructed to do so.
• 4. Never touch or taste any chemical unless instructed to
do so.
• 5. Keep all lids closed when chemicals are not in use.
• 6. Immediately rinse off any chemicals that get on your
skin or clothes. Then tell me!
Heat Safety
• 1. Whenever you see this symbol, you will know that you
should put on heat-resistant gloves to avoid burning your
hands.
• 2. When heating a test tube or bottle, always point it away
from you and others. Chemicals can splash or boil out of a
heated test tube.
Eye and Face Safety
• 1. Whenever you see this symbol, you will know that you are
performing an experiment in which you must take precautions
to protect your eyes and face by wearing safety goggles.
• 2. When you see this symbol, you should also make sure to
pull your hair back away from your face for better vision and
to keep from getting chemicals in it.
Sharp Instrument Safety
• 1. Whenever you see this symbol, you will know that you are
working with a sharp instrument.
• 2. Always use single-edged razors; double-edged razors are
too dangerous.
• 3. Handle any sharp instrument with extreme care. Never cut
any material toward you; always cut away from you.
• 4. Immediately notify me if you cut yourself.
• 5. Know the location of the first aid kit!
Electrical Safety
• 1. Whenever you see this symbol, you will know that you are
using electricity in the lab.
• 2. Never use long extension cords to plug in an electrical
device. Do not plug too many devices into one outlet. Make
sure not to run cords across the sink.
• 3. Never touch an electrical appliance or outlet with wet
hands. Do not put anything in an outlet that should not be
plugged in.
Animal Safety
• 1. Whenever you see this symbol, you will know that you are
working with animals.
• 2. Do not cause pain, discomfort, or injury to a live animal. Do
not mutilate a dead animal. Do not make any unauthorized
cuts on a dissection animal.
• 3. Wash your hands thoroughly after handling animals or their
cages.
Review
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What is the location of the fire extinguisher?
What is the purpose of the red stop button?
What is the location of the first aid kit?
What color is the safety shower?
What is the location of the fire blanket?
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What does this symbol mean?
What should you keep in mind when you see it?
What does this symbol mean?
What should you keep in mind when you see it?
What does this symbol mean?
What should you keep in mind when you see it?
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What does this symbol mean?
What should you keep in mind when you see it?
What does this symbol mean?
What should you keep in mind when you see it?
What does this symbol mean?
What should you keep in mind when you see it?
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What does this symbol mean?
What should you keep in mind when you see it?
What does this symbol mean?
What should you keep in mind when you see it?
Should you ever eat or drink in the lab?
When should you read the lab directions?
Measurement in Science
Unit 1, Part 2
Units of Measurement
• Since mathematics is the language of science (just as poetry is
the language of love), and mathematical models rely on
accurate measurements, it’s important that we’re all speaking
the same language. Why?
• Scientists (and you) use the international system of
measurements, or SI, for labeling observations, calculations,
and measurements.
Consistency in Measurements
• When all scientists (and you) use the same
units for measuring data, sharing data and
results is easier.
• The SI is based on the metric system, and it
uses seven SI base units, some of which are
listed in the following table.
SI Base Units
Quantity
Unit
Abbreviation Tool Used
Length
Meter
m
Metric ruler
Mass
Gram
g
3-beam
balance
Temperature Kelvin
K
C
thermometer
Time
Second
s
clock
Volume
Liter
L
g.c.or ruler
Current
Amp
A
N/A
Amount
Mole
Mol
N/A
SI Prefixes
• The previous table listed the base units for the
more common metric measurements.
• However, the next tables will list some prefixes
used for very small measurements and very
large measurements.
Prefixes for Large Measurements
Prefix
Symbol
Meaning
Deka
dk or da
Ten
Multiple of
Base Unit
10
Hecto
h
Hundred
100
Kilo
k
Thousand
1000
Mega
M
Million
1000000
Giga
G
Billion
1000000000
Prefixes for Small Measurements
Prefix
Symbol
Meaning
Deci-
d
tenth
Multiple of
Base Unit
0.1
Centi-
c
hundredth
0.01
Milli-
m
thousandth
0.001
Micro-

millionth
0.000001
Nano-
n
billionth
0.000000001
Easy Mnemonic
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KING (kilo)
HECTOR (hecto)
DIED (deka)
UNEXPECTEDLY (unit)
drinking (deci)
chocolate (centi)
milk (milli)
Dimensional Analysis: Conversions
• If you are converting a larger unit to a smaller
unit, multiply the measurement to get a
bigger number. To write 1.85 m as cm,
multiply by 100 to get 185 cm.
• If you are converting a smaller unit to a larger
unit, divide the measurement to get a smaller
number. To write 185 cm as m, divide by 100
to get 1.85 m.
Practice Problems
• Write 550 mm as m.
• Write 3.5 s as ms.
• Convert 1.6 kg to g.
Parts of the Microscope
• A compound microscope is made up of several
parts. Some you should be familiar with are:
• Stage - where the slide sits
• Iris - adjusts the amount of light allowed in
• Fine adjustment knob - focuses image
• Coarse adjustment knob - moves stage
• Eyepiece - what you look through
• Objective lenses (low, medium, high) - three
lenses with different magnification
• Mirror or lamp - light source
Microscope Calculations
• Resolving power - the ability of a lens to distinguish
between two objects (the higher the resolving
power, the better able you are to see separate
objects) or objects at different depths.
• To calculate total magnification: multiply the
eyepiece magnification (which is always 10) by the
lens you’re looking through (usually 4, 10 or 40).
That gives you a total magnification of 40 on low
power, 100 on medium power, or 400 on high power.
Methods of Science
Unit 1, Part 3
Theories and Laws
• A scientific theory is a hypothesis that has been
supported many times and stands the test of time,
but can change as new information is gathered
(example: the theory of evolution).
• A scientific law is a statement about events that
always occur in nature (example: an apple will fall
down from a tree, not fly up from it - the law of
gravity).
• Science can’t explain or prove all!
Methods of Science
Science as a process:
Science is a process that produces a body of
knowledge about nature.
Applied Science:
Science is used to apply general knowledge to real
problems, or technology.
The Scientific Method
• In the scientific method, critical thinking is used to
solve scientific problems.
• What is critical thinking? The ability and willingness
to assess claims critically and to make judgments on
the basis of objective and supported reasons.
• The scientific method is a great way to help you
organize your thinking about questions that might be
considered scientific.
Step One:State the Problem
• Most of learning happens by asking questions. Why
is the sky blue? How does popcorn pop? What time
is it when the sun is in mid-sky?
• Your purpose or problem needs to be stated as a
clear and specific question so you can answer it
clearly and specifically.
• Bad example: is fertilizer good for plants?
• Good example: does adding fertilizer to plants make
them grow taller?
Step Two: Gather Information
• The purpose for gathering information before
beginning your experiment or developing a
hypothesis is that it allows you to make informed,
educated proposed solution.
• This is best done in the library, as there are
innumerable resources available.
• It’s very important that you check for accuracy in
your sources, and that you use a variety of media,
such as book, magazines, professional journals, and
internet.
Step Three: Form A Hypothesis
• A hypothesis is not an “educated guess”, but an
informed, well-researched proposed solution.
• It should be written in “if…then” format.
• For example, “If fertilizer is added to a plant, then it
will grow taller.”
• The “if” statement is your independent variable.
(whether fertilizer is added)
• The “then” statement is your dependent variable. (its
effect on the plant’s height)
Step Four: Design and Conduct
Experiment
• Set up procedures for experiment before beginning
it. Always describe the experiment so that another
person reading your plan could repeat it.
• An experiment can be a survey, an observation, a
test, or an actual lab test.
• Remember, during this stage, it’s important to keep
other variables constant and only change one at a
time. (controlled experiment)
Step Five: Collect, Organize, Analyze
Data
• During this stage, you will receive all sorts of
information to make sense of.
• In order to present it in an orderly manner, graphs,
charts, and tables are useful.
• Line graphs are best for showing continuous growth.
• Bar graphs are best for comparing individual sets of
data.
• Pie charts are best for showing parts of a whole.
More on Graphs
• Every graph needs:
– Title that includes
both variables
– X and Y axis labels
– Key
– Units of Measurement
– Accurate drawing
Step Six: Form A Conclusion
• Your conclusion should answer the question
presented in step one.
• For example, adding fertilizer to plants made them
grow taller.
• This is also an opportunity to make suggestions
about improving your experiment, how to get more
accurate data, changing variables, and things that
could have gone wrong with your experiment.
Step Seven: Repeat!
• In order to insure accuracy of your results, you
must show that, if your experiment is
repeated, one would get the same outcome.