Nature of Science
Unit 1
•Characteristics of Life
•Scientific Method
•History of the Scientific Method
•Organization of Living Things
Warm Up:
What is the
Nature of Science?
What is Science
Observing
Characteristics
Of Life
Explain
Interpret
Scientific Tools
And Procedures
Metric
System
Microscopes
What is the Nature of Science?
Knowledge attained
through study or
practice
Set of methods or
processes
Using observation and
experimentation to
describe and explain
the natural world
Organized way of
using evidence to
learn about the
natural world.
Do you agree or disagree?
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•
•
•
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Science demands evidence
Science is a social activity
Science is a blend of logic and imagination
Scientific ideas are subject to change
Scientific ideas are durable
Science avoids bias
The natural world is understandable
Section 1-2
Designing an Experiment
State the Problem
Analyze Results
Form a Hypothesis
Draw a Conclusion
Set Up a Controlled Experiment
Publish Results
Record Results
Scientific Method
What is the scientific method?
It is a _______________ that is used to find _______________ to questions about
the world around us.
Is there only one “scientific method”?
No, there are several versions of the scientific method. Some versions have more
___________, while others may have only a few. However, they all begin with the
identification of a ______________ or a ____________________ to be answered
based on observations of the world around us and provide an ________________
method for conducting and analyzing an experiment.
What is a hypothesis?
It is an ________________ ___________ based on observations and your
knowledge of the topic.
What is data?
It is __________________ gathered during an experiment.
Defining the Variables
• Independent Variable: what you change, this is what you
control
• Dependent variable: the factor in an experiment that you
want to observe, the data or what you measure
• Experimental Group: How will each group be different?
(the group exposed to the independent variable)
• Constants: the things that stay the same for all the
experimental groups
• Control Group: the group that you compare to
– No treatment
– Experimenter Selected group
Scientific Method
__________
What do you want to know or explain? Use observations you have made to
write a question that addresses the problem or topic you want to investigate.
_____________________
What do you think will happen? Predict the answer to your question or the
outcome of the experiment.
________________
How will you test your hypothesis? Develop a procedure for a reliable
experiment and address safety rules.
____________________________________
Follow the steps in your procedure to perform your experiment.
Record data and observations!
______________________________________________________
Is the data reliable? Does your data and observations from the
experiment support your hypothesis?
______________________________
Write a conclusion that summarizes the important parts of your
experiment and the results.
Perform an Experiment
Follow the steps in your procedure to perform your experiment. Record data
and observations
Analyze the Data
Is the data reliable? Does your data and observations from the experiment
support your hypothesis?
_______________________________________
Is your data inaccurate or the
experiment flawed?
____________________
Rewrite your procedure
to address the flaws in
the original experiment.
Communicate the Results
Write a conclusion that summarizes the important parts of your experiment
and the results.
Experimental Design Template
Problem Statement: (Stated as a testable question)
Hypothesis: (If....Then statement describing the effect that changing
the independent variable has on the dependent variable)
Independent Variable (IV):
Dependent Variable (DV):
Constants:
Controls:
Experimenter selected control:
Graphing
Living vs.
Non-Living
Prior to the 1600's many people believed
that nonliving things could spontaneously
turn into living things. For example, it was
believed that piles of straw could turn into
mice. That is obviously not the case.
Redi’s Experiment on Spontaneous
Generation
OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.
HYPOTHESIS: Flies produce maggots.
PROCEDURE
Uncovered jars
Controlled Variables:
jars, type of meat,
location, temperature,
time
Covered jars
Several
days pass
Manipulated Variables:
gauze covering that
keeps flies away from
meat
Responding Variable:
whether maggots
Maggots appear
No maggots appear
appear
CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous
generation of maggots did not occur.
Needham
• Looked at growth in broth.
• Did not believe Redi’s experiment.
• Tried to prove that spontaneous generation
could occur under the right conditions.
• Assumption: heating the gravy killed all the
microorganisms
Spallanzani’s Experiment
Hypothesis?
Gravy is boiled.
Flask is
open.
Gravy is teeming
with microorganisms.
Gravy is boiled.
Flask is
sealed.
Gravy is free of
microorganisms.
Independent Variable?
Dependent Variable?
Controls?
Pasteur’s Experiment of Spontaneous Generation
Broth is boiled.
Broth is free of
microorganisms
for a year.
Curved neck
is removed.
Broth is
teeming with
microorganisms
.
Pasteur
Why did microorganisms grow after Pasteur broke
the neck of the flask?
Biogenesis (generating from life)
All Living things come from other living things!
Theory:
a well tested explanation that unifies a
broad range of observations
• Can a Theory change over time?
Yes, as new evidence is uncovered, a
theory may be revised or replaced
Scientific Theory vs. Scientific Hypothesis
Scientific Laws
-generalizations derived from facts
• Scientific knowledge is based on observation
and inference.
• Scientific laws describe what happens, but not
how.
• Scientific laws are not meant to be absolutely
true for every circumstance.
• Scientific laws may change with new evidence.
Characteristics of Living Things
Characteristic
Examples
Living things are made up of units called
CELLS.
Living things reproduce.
Living things obtain and use materials and
energy.
Many microorganisms consist of only a single cell
(unicellular). Animals and trees are multicellular.
Maple trees reproduce sexually. A hydra can
reproduce asexually by budding.
Flies produce flies. Dogs produce dogs. Seeds from
maple trees produce maple trees.
Butterflies begin life as eggs, then become caterpillars,
and then become adult butterflies.
Plants obtain their energy from sunlight. Animals
obtain their energy from the food they eat.
Living things respond to their environment.
Leaves and stems of plants grow toward light.
Living things maintain a stable internal
environment.
Despite changes in the temperature of the
environment, a robin maintains a constant body
temperature.
Taken as a group, living things change
over time.
Plants that live in the desert survive because they have
become adapted to the conditions of the desert.
Living things are based on a universal
genetic code.
Living things grow and develop.
Levels of Organization
Biosphere
The part of Earth
that contains all
ecosystems
Biosphere
Ecosystem Community and
its nonliving
surroundings
Hawk, snake, bison, prairie dog, grass, stream, rocks, air
Community Populations that
live together in a
defined area
Hawk, snake, bison, prairie dog, grass
Population
Group of
organisms of one
type that live in
the same area
Bison herd
Organism Individual living
thing
Bison
Tissues, organs,
Groups of and organ
Cells
systems
Brain
Nervous tissue
Cells
Nervous system
Smallest functional
unit of life
Nerve cell
Groups of atoms;
smallest unit of
Molecules most chemical
compounds
Water
DNA
Designing an Experiment
State the Problem
Analyze Results
Form a Hypothesis
Draw a Conclusion
Set Up a Controlled Experiment
Publish Results
Record Results