The document outlines safety procedures and guidelines for conducting scientific experiments in a laboratory setting. It describes the scientific method, including key steps like making observations, developing hypotheses, experimentation, analyzing results, and communicating findings. Safety norms are also discussed, such as wearing protective equipment, proper handling and disposal of materials, and understanding hazard pictograms. The overall document provides an introduction to performing experiments safely and following the scientific process.

1. Biology & Geology
ampliation
4º ESO
Pablo León Cruz www.biogeosfera.es

2. Unit 1
The scientific method
and the laboratory
work
Pablo León Cruz www.biogeosfera.es

3. Definition of science
Science consists in the careful study of the structure and
behaviour of the physical world, especially by watching,
measuring, and doing experiments. These experiments
contribute to the development of theories that describe and
explain the natural phenomena.

4. The scientific method
The scientific method consists of a series of steps that must be
followed to carry out an experiment or to obtain valid
information from a scientific point of view.
The main characteristics of a valid scientific method are
reproducibility and falsifiability.
An experiment is reproducible if anyone can follow the
steps and come up with the same results.
An experiment is falsifiable if a change in any of the
elements of the experiment can alter it and contradict the
expected result.

5. The scientific method
The results of an experiment are generally evaluated by other
scientists who repeat the original experiment and check if their
experiment has similar results to those obtained by the
scientists who did it for the first time.

6. Steps in the scientific method
Observation of a phenomenon
Reasearch and data collection
Hypothesis formulation
Experimentation
Analysis of results
Drawing a conclusion
Communication of results
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7. Steps in the scientific method
1.Observation of a phenomenon: The first step involves
identifying an event or phenomenon worthy of study and
making an objective description of the facts. Also this is the
moment for asking questions which answer is not known.
2.Reasearch and data collection: After identifying the event or
phenomenon, it is necessary to carry out a search for
information on the topic to be investigated and select the data
that may be useful or interesting.
3.Hypothesis formulation: An hypothesis is a provisional
answer or an idea that allows us to answer the proposed
questions or to explain the studied phenomenon. An
hypothesis has to be able to be tested through experiments.

8. Steps in the scientific method
4.Experimentation: The hypothesis has to be tested by
conducting an experiment. The experiment is a way of testing
our predictions and should be able to be repeated by another
scientist.
5.Analysis of results: The findings of the experiment have to be
analyzed to determine if the formulated hypothesis is correct.
If the results do not support the hypothesis, it is necessary to
reformulate it and carry out new experiments.
6.Drawing a conclusion: A conclusion explains if what we
thought would happen actually happened. It explains the
experiments carried out and the results obtained that support
the hypothesis.
7.Communication of results: The findings have to be
communicated in a written report, in a presentation during a
scientific event or in a scientific journal.

9. Security norms in the lab
Regarding the order and cleanliness
 Always wash your hands with soap or disinfectant before
leaving the laboratory, as well as after handling biological
material.
 Organize the material as you carry out the work, keeping the
work tables clean and avoiding the accumulation of dirt, dust
or remains of the products used.
 Clean, store and properly preserve the material and
equipment after each laboratory practice, placing everything
in its corresponding place.

10. Security norms in the lab
Regarding personal safety
 Wear a lab coat, as it prevents possible spills of chemical
substances from reaching the skin and at the same time
protects against possible damage to clothing.
 If you are not wearing a lab coat, try to avoid loose clothing,
shorts, sandals, etc.
 If you have long hair, make a ponytail to avoid possible
accidents.
 Take off all personal accessories that may include risks of
accidents, such as rings, bracelets, necklaces and caps.

11. Security norms in the lab
Regarding the use of flammable material
 Never light a lighter if you smell gas and neither before
checking that there is no flammable liquid near you.
 When heating test tubes directly over a flame, do not leave
the tube still over the flame during the process.
 If a fire starts in a container, cover it with a lid or a larger
inverted container to smother the flame by preventing the
entry of air.
 If a flaming liquid is spilled, as it can happen with an alcohol
lighter, do not use water to extinguish it. Use the fire
extinguisher, pour sand, or cover it with a damp cloth.

12. Security norms in the lab
Regarding the use of glassware
 Never direct the mouth of the heated test tube towards
another person, as there is a danger of a violent projection of
its contents.
 When heating test tubes directly over a flame, do not leave
the tube still over the flame during the process.
 Hot glass should be kept out of the way until it is cool. In the
case of test tubes, a test tube rack can be used.
 Make sure the glass utensils are not broken before using
them.

13. Security norms in the lab
Other aspects to consider (I)
 Do not taste any chemical product unless expressly instructed
by the teacher.
 To perceive the odors of the reagents, or those given off in an
experiment, draw the vapor with your hand, directing it
towards your nose.
 Do not wet minerals, as some of them are soluble and could
be damaged when they come into contact with water.
 Some minerals (and rocks with these minerals) are toxic, so
wash your hands with soap after handling them.

14. Security norms in the lab
Other aspects to consider (II)
 Handle fossils very carefully to avoid deterioration.
 Do not mess up the items from the collections when you take
them out of the boxes and make sure that each sample is in its
correct place when you put it back.
 If you are going to perform a dissection, store the biological
material in a refrigerator until the moment of the practice to
avoid bad odors.
 At the end of the dissection, dispose of all organic remains in
a bag, which must be knotted and placed in a container.

15. Security norms in the lab
Other aspects to consider (III)
 Wash well with soap and disinfect tools such as scalpels,
scissors or mounted needle with bleach.
 Do not put your hands in your mouth while handling
biological material due to the possible presence of bacteria
and protozoa.
 Do not dispose directly into the sink products that react with
water, are flammable, have a bad odor or are difficult to
biodegrade.
 Do not dispose products or solid waste into the sink.

16. Hazard pictograms in the laboratory
 Health hazard: A cancer-causing agent or a substance with
respiratory, reproductive or organ toxicity that causes
damage over time.
 Exclamation mark: An immediate skin, eye or respiratory
tract irritant, or narcotic.
 Corrosion: Materials causing skin corrosion/burns or eye
damage on contact, or that are corrosive to metals.

17. Hazard pictograms in the laboratory
 Flame: Flammable substances liable to self ignite when
exposed to water or air or which emit flammable gas.
 Flame over circle: Identifies oxidizers, substances that
facilitate burning or make fires burn hotter and longer.
 Skull and crossbones: Substances, such as poisons and
highly concentrated acids, which have an immediate and
severe toxic effect.

18. Hazard pictograms in the laboratory
 Gas Cylinder: Gases stored under pressure, such as ammonia
or liquid nitrogen.
 Environmental Hazard: Chemicals toxic to the environment
and aquatic wildlife.
 Exploding Bomb: Explosives and highly unstable material at
risk of exploding even without exposure to air (self-
reactives).