NOTES: Chapter 1.1
What is Science?
What is a “FACT?”
• Something that can be proved or verified by observation or measurementmeasurement
What are some other types of facts
besides the kind you just listed?
Examples: historical facts, scientific
facts, facts read in the newspaperfacts, facts read in the newspaper
Is it possible for a
fact to change?
• It depends on the type of fact.
• Historical facts: No. They already happened.
• Scientific facts: Yes. These facts are based on current knowledge & since we will never know everything, scientific facts can change when new scientific facts can change when new data is discovered.
Science is flexible!
● It is a process and a way of looking at
the world around us. Science explains the
world today, based on research and
evidence we have collected so far.
1.1: What Methods are Used in Science?
What is the Nature of Science / Biology?
Vocabulary:
�Science�Science
�Observation
�Data
�Inference
�Hypothesis
The Goal of Science…
• To investigate and understand nature
• To explain events in nature• To explain events in nature
• To use those explanations to makeuseful predictions
The scientific method makes science different from non-
science.
Science is an organized way
of using EVIDENCE to learn
about the natural world
FossilsDNA
Scientific Method1. Observation: use senses
2. Gather Data from Observations
Quantitative: numbers
(ex: plant height= 32cm)
Qualitative: characteristics
(ex: red hair)
3. Form a Hypothesis using Prior Knowledge Data
4. Test Hypothesis by Observation & Experiment
5. Record & Analyze Data (charts & graphs)
6. Form a Conclusion based on Evidence
Evidence & Observations
How do you make
observations?observations?
Observation vs. InferenceBe careful with your observations!
• Observation: use of one or more of the senses to gather information
• Ex: water tested at 1 site at a lake shows that
the bacteria count is lowthe bacteria count is low
• Inference: A conclusion or interpretation drawn from observationand prior knowledge
• Ex: the entire lake has a low bacteria count
Hypothesis
• Definition: possible explanation for a set of observations
• Useful only if it can be tested!
• Arise from prior knowledge, logical • Arise from prior knowledge, logical inferences, or imaginative guesses
• A hypothesis always has value!
So you’ve made an observation…
• The information gathered from observations is
called…?
• Data can be divided into two types
• Qualitative: descriptions (things NOT • Qualitative: descriptions (things NOT
counted/measured)
• Quantitative: using numbers
Which of the following is an
inference?
a) The plant is yellowish and wilting
b) The plant should be moved to where there is more sun
c) The plant needs waterc) The plant needs water
d) B and C only
e) None of the above
Why Do Scientists Write Lab
Reports?
• So their work can be replicated by
either themselves or other
researchers
– WHY? to assure us that the results – WHY? to assure us that the results aren’t due to chance & that they are accurate
1.2: Science in Context
Vocabulary:
�Controlled experiment
Independent variable�Independent variable
�Dependent variable
�Theory
Remember, the Scientific Method is…
an organized way of
using evidence to
learn about the learn about the
natural world
Steps of the Scientific Method
• observations which lead to a problem
• form a hypothesis (possible explanation for
observations)
• test hypothesis by setting up a CONTROLLED • test hypothesis by setting up a CONTROLLED
EXPERIMENT
• Controlled Experiment – isolate and test effects
of a single variable; everything else is constant
(remains identical between the 2 experiment set
ups)
• Control: the standard in which all the conditions
are kept the same
• Independent Variable: the condition that is • Independent Variable: the condition that is
changed because it affects the outcome of the
experiment
• Dependent Variable: the condition that results
from changes in the independent variable
Prior to the Scientific Method:• Philosophers such as Aristotle tried to explain
their observations of the world though
reasoning
• They thought that special “vital” forces
brought some living things into being from
non-living thingsnon-living things
Recipe for Bees:1. Kill a bull during the first thaw
of winter.
2. Build a shed.
3. Place the dead bull on branches
& herbs inside the shed.
4. Wait for summer. The decaying
body of the bull will
produce bees.
• This idea is called…
SPONTANEOUS GENERATION
– Life from non-life
• It was accepted for centuriescenturies
– Ex: Maggots are formed
from meat; mice from
grain; beetles from cow
dung
Redi’s Experiment on Spontaneous Generation
Independent VariableWhat did Redi change?
Dependent VariableWhat changed as a result & became his data?
What were the variables?
Controlled variables
• jars, types of meat, location, temperature
Independent variable
• gauze coverings• gauze coverings
Dependent variable:
• if maggots appeared or not
Pasteur’s Test of Spontaneous Generation
Was air needed for the spontaneous generation of life?
“ A remarkable
problem solver”
Pasteur’s Test of Spontaneous
Generation
• Pasteur’s experiment:
–Expose the flasks (with boiled broth) to airbroth) to air
–BUT: Protect one sample of broth from microorganisms by curving the neck
Pasteur’s Test of Spontaneous
Generation
• When Pasteur broke the neck of the flask, broth quickly was filled with microorganismsfilled with microorganisms
• His work convinced everyone: ALL living things come from other living things!!
When does a hypothesis become a
theory?
● when a hypothesis is tested and confirmed often enough that it is unlikely to be disproved by future tests
● In science, the word theory applies to a ● In science, the word theory applies to a well-tested explanation that unifies a broad range of observations
● a theory may be revised or replaced as new evidence is uncovered… SCIENCE IS A PROCESS
For your information…
• Theories and laws are DIFFERENT kinds of knowledge
• LAW = generalizations/description of a pattern in nature
• THEORY= explanation of those generalizations
Theories do NOT become laws
(or vice versa)
What is a controlled experiment?
a) An experiment in which the scientist controls
every aspect and records all data accurately
b) An experiment in which there is an
experimental group and a controlled groupexperimental group and a controlled group
c) An experiment in which all groups tested have
many differences between them (they are all
considered experimental groups)