1-1 What Is Science
3 Goals of Science
Science is an organized way of
1. Provide
using evidence to learn about explanations for the
the natural world.
natural world
Science is a process, not a
“thing.”
Explain this statement.
2. Use explanations
to understand
patterns
3. Make useful
predictions about
natural events
The Scientific Method
The scientific method is not a simple set of steps
followed by all scientists, all of time.
The scientific method just describes a general style
of investigation.
Example: In the 17th century there was a debate
over what caused food to spoil.
– Spontaneous Generation: living things, like
maggots, could arise from nonliving
substances.
– Biogenesis: living things can only come from
other living things.
http://www.accessexcellence.org/RC/AB/BC/Spontaneous_Generation.php
1. Observing and Asking Questions
• Observation – involves one or more senses to
gather data
It is important to use all of your senses
to collect as much data as you can.
Sight isn’t always enough!
1. Observing and Asking Questions
Science usually begins with observations:
– Quantitative – involves numbers, counting or measuring
3 meters
50 kilograms
35 degrees Celsius
– Qualitative – involves characteristics that cannot easily
be measured or counted, color or texture (describable)
It smells like fresh baked cookies
This feels cold
This sounds really loud
Inference – a logical interpretation of data based on
prior knowledge
We don’t observe an inference. We use observations to
create inferences.
Quick practice
Observations:
• I hear people screaming
• I smell cotton candy, popcorn, and
hamburgers
• I see a lot of people
Inference = ?
What are some qualitative and quantitative observations
you can make of these skulls?
How about an inference based upon your observations?
Goal: Make predictions using
observations
Create an experiment on
paper
Warm up: Make a
qualitative and quantitative
observation from the
picture
• Look at these two sets of
animal tracks.
• List 3 OBSERVATIONS
• Make an INFERENCE
Make 3 OBSERVATIONS
Make an INFERENCE
Make 3 OBSERVATIONS
Make an INFERENCE
1. Observing and Asking Questions
– Example Observation: Flies
frequently land on the meat a few
days before maggots appear.
The Observation leads to a question.
– Example Question: Are the maggots
produced by flies?
The Scientific Method
2. Inferring and Forming a hypothesis
– Hypothesis: A possible
explanation for a set of
observations.
– Not just an educated guess
– Must be a testable statement
Example: The maggots come
from the flies not the rotting
meat.
The Scientific Method
3. Setting up a controlled experiment
Variables: factors that can change.
– Independent (manipulated) variable: the variable that
the experimenter changes.
– Dependent (responding) variable: changes in response
to the independent variable. Can be measured.
Francesco Redi used this simple
experiment to test the hypothesis.
What is the independent variable?
What is the dependent variable?
The Scientific Method
Experiments are usually divided into two groups:
– Experimental Group – the independent variable has
been changed.
– Control Group – exactly the same as the experimental
group except the independent variable has not been
changed. Experiment without the variable.
Why is the control group important for a good
experiment?
What is the
experimental group?
What is the control
group?
Scientific Method
5. Drawing Conclusions
– Researchers use data as
evidence to determine if the
hypothesis needs to be
supported or refuted.
– Ex: Maggots only appeared in
the flask that was open to flies.
– Do the results support the
When Experiments Are Not Possible
• How do we learn about
animal behavior in the
wild?
Answer: Field studies –
watching the animals
without disturbing them.
• Some experiments are
prevented because of
ethical considerations.
• Think of an example.
Stanford Experiment
Elements of a Good Graph
• Scaling and Increments
are even
• Neatness and Accuracy
counts
• Title (should include
I.V./D.V.)
• Labeling of X and Y axis
• No squiggle line
• Use a ruler
“DRY MIX”
D = dependent variable
R = responding variable
Y = graph information on
the vertical axis
M = manipulated variable
I = independent variable
X = graph information on
the horizontal axis
Number of books
18
16
14
12
10
number of books
8
6
4
2
0
coke
orange
sprite
Dr. P
Birch
http://gator.gatewayk12.org/~smcgrail/myweb/powerpoint/misleading_graphs/here_are_some_examples_of_mislea.htm
1-2 Communicating Results
Publishing your research in scientific journals allows scientists
to share ideas and to test/evaluate each other’s work.
– Scientist, John Needham, reviewed Redi’s experiment
and thought that he could show that bacteria grows
through spontaneous generation.
He boiled broth in an open
flask to kill all bacteria.
After several days more
bacteria grew in the flask.
What is the problem with
this experiment?
Communicating Results
• Scientist, Lazzaro Spallanzani, reveiwed Needham’s
experiment and hypothesized that the bacteria could
have come from the air.
– He repeated Needham’s experiment but he sealed
the flasks.
– Showed that bacteria did not grow in the broth, and
supported biogenesis.
Scientists did not accept
Spallanzani’s conclusions.
Why not?
Louis Pasteur
• Scientist continued to debate about spontaneous
generation until 1859.
• Because scientists published their experiments they
critique and improve on the design.
• Louis Pasteur repeated the experiment but this time he
used a flask that would let air in but keep out bacteria.
Did Pasteur’s results support
biogenesis or spontaneous
generation?
Explain how this process of
communicating results
improves our understanding?
How a Theory Develops
• Theory – a well-tested explanation that ties together
many different observations and hypotheses.
– No theory is considered absolute truth because
science is always changing.
– Biogenesis is a well tested theory
– How is the scientific use of the word “Theory”
different than the everyday use of the word theory.
Scientific Method
Scientific Terms
• Law: A statement or
equation that summarizes
observations without
explaining them.
Examples:
– Law of conservation of matter
– Laws of inheritance