Chapter Introduction
Lesson 1
Understanding
Science
Lesson 2
Measurement
and Scientific
Tools
Lesson 3
Case Study
Chapter Wrap-Up
How can science provide
answers to your
questions about the
world around you?
Understanding Science
• What is scientific inquiry?
• What are the results of scientific
investigations?
• How can a scientist prevent bias in a
scientific investigation?
Understanding Science
• science
• technology
• observation
• scientific theory
• inference
• scientific law
• hypothesis
• critical thinking
• prediction
What is science?
• Science is the investigation and
exploration of natural events and of the
new information that results from those
investigations.
• People use reasoning, creativity, and
skepticism in their daily lives to solve
problems.
Branches of Science
Biology, or life science, is the study of all
living things.
biology
from Greek bios, means “life”;
and logia, means “study of”
Branches of Science (cont.)
• The study of Earth, including landforms,
rocks, soil, and forces that shape Earth’s
surface, is Earth science.
• The study of chemistry and physics is
physical science.
Scientific Inquiry
As scientists study the natural world, they
usually use certain skills, or methods.
Scientific Inquiry (cont.)
A scientist uses a sequence of skills and
methods in an investigation.
Scientific Inquiry (cont.)
• Observations often are the beginning of
the process of science.
• An observation is using one or more of
your senses to gather information and
take note of what occurs.
Scientific Inquiry (cont.)
• A possible explanation about an
observation that can be tested by
scientific investigations is a hypothesis.
• A prediction is a statement of what will
happen next in a sequence of events.
Scientific Inquiry (cont.)
• When you test a hypothesis, you often
are testing your predictions.
• If your prediction is not confirmed, your
hypothesis might need revision.
Scientific Inquiry (cont.)
What is scientific inquiry?
Scientific Inquiry (cont.)
• The next step in a scientific investigation
is to organize and analyze your data.
• You must determine whether inferences
can be made or conclusions drawn from
the data.
• An inference is a logical explanation of
an observation that is drawn from prior
knowledge or experience.
• If your hypothesis is supported by the
data, you can repeat the experiment to
confirm the results.
• If your hypothesis is not supported, you
may need to modify it.
Scientific Inquiry (cont.)
An important step in scientific inquiry is
communicating results.
Results of Scientific Inquiry
• In science, you perform scientific inquiry
to find answers to questions.
• The practical use of scientific knowledge,
especially for industrial or commercial
use is technology.
• Many times, scientific investigations
answer the questions: who, what, when,
where, or how.
Results of Scientific Inquiry (cont.)
What are the results of
scientific investigations?
Scientific Theory and Scientific Laws
• A scientific theory is an explanation
of observations or events based on
knowledge gained from many
observations and investigations.
• A scientific law describes a pattern or
an event in nature that is always true.
Scientific Theory and Scientific Laws
(cont.)
• Critical thinking is comparing what you
already know with the information you
are given in order to decide whether you
agree with it.
• To prevent bias in an investigation,
sampling, repetition, and blind studies
can be helpful.
Scientific Theory and Scientific Laws
(cont.)
How can a scientist prevent bias
in a scientific investigation?
Scientific Theory and Scientific Laws
(cont.)
• Questions about personal opinions,
values, beliefs, and feelings cannot be
answered scientifically.
• Scientists follow safety procedures when
they conduct investigations.
• Ethics are especially important when
using living things during investigations.
Which is the study of chemistry
and physics?
A. biology
B. Earth science
C. life science
D. physical science
Which term refers to a statement
of what will happen next in a
sequence of events?
A. hypothesis
B. inference
C. observation
D. prediction
Which refers to comparing what you
already know with the information
you are given in order to decide
whether you agree with it?
A. critical thinking
B. inference
C. observation
D. scientific law
Measurement and Scientific
Tools
• What is the difference between
accuracy and precision?
• Why should you use significant digits?
• What are some tools used by
scientists?
Measurement and Scientific
Tools
• description
• accuracy
• explanation
• precision
• International
System of
Units (SI)
• significant digits
Description and Explanation
• A description is a spoken or written
summary of observations.
• An explanation is an interpretation of
observations.
• When you explain something, you try to
interpret your observations, which can
lead to a hypothesis.
The International System of Units
• The International System of Units (SI)
is an internationally accepted system for
measurement.
• All SI units are
derived from seven
base units.
The International System of Units (cont.)
• A prefix can be
added to a base
unit’s name to
indicate either a
fraction or a multiple
of that base unit.
• Prefixes are based
on powers of ten,
such as 0.01 and
100.
• Accuracy is a description of how close
a measurement is to an accepted or
true value.
• Precision is a description of how
similar or close measurements are to
each other.
The data taken by student A are more
accurate because each value is close to
the accepted value. The data taken by
student C are more precise because the
data are similar.
The International System of Units (cont.)
How do accuracy and precision
differ?
Measurement and Accuracy
• All measurements have some
uncertainty.
• The tools used to make measurements
limit the accuracy of the measurements.
Significant Digits
• Significant digits are the number of
digits in a measurement that are known
with a certain degree of reliability.
• The significant digits in a measurement
include all digits you know for certain
plus one estimated digit.
Significant Digits (cont.)
Using significant digits lets others know
how certain your measurements are.
Significant Digits (cont.)
Why should you use significant
digits?
Scientific Tools
Science journals are for
recording descriptions,
explanations, plans, and
steps used in scientific
inquiry.
Corbis
Scientific Tools (cont.)
A triple-beam balance or
a digital balance is used
by scientists to measure
mass.
The McGraw-Hill Companies, Inc./Stephen Frisch, photographer
Scientific Tools (cont.)
A thermometer
measures the
temperatures
of substances.
The McGraw-Hill Companies Inc./Ken Cavanagh Photographer
Scientific Tools (cont.)
Flasks, beakers,
petri dishes, test
tubes, and specimen
jars are used as
containers.
Scientific Tools (cont.)
• Graduated cylinders are
used to measure the volume
of a liquid.
• The unit of measure for liquid
volume is the liter (L) or
milliliter (mL).
Scientific Tools (cont.)
Microscopes, such
as dissecting
microscopes and
compound light
microscopes,
enable you to
observe small
objects that you
cannot observe
with just your eyes.
Photodisc/Getty Images
Scientific Tools (cont.)
Scientists use computers to compile,
retrieve, and analyze data for reports.
Tools Used by Life Scientists
• A magnifying lens is a hand-held lens
that magnifies, or enlarges, an image of
an object.
• To observe items using a compound light
microscope, you must place it on a thin,
rectangular piece of glass called a slide.
Tools Used by Life Scientists (cont.)
• Scientists use
dissecting tools,
such as scalpels and
scissors, to examine
tissues, organs, or
prepared organisms.
Ingram Publishing/SuperStock
• A pipette is a small
glass or plastic tube
used to draw up and
transfer liquids.
Photodisc Collection/Getty Images
Tools Used by Life Scientists (cont.)
What are some tools used by
life scientists?
Which term refers to a description
of how close a measurement is to
an accepted or true value?
A. accuracy
B. explanation
C. precision
D. significant digit
Which can be added to a base
unit’s name to indicate either a
fraction or a multiple of that base
unit?
A. SI unit
B. significant digit
C. prefix
D. description
Which of these is used by
scientists to measure mass?
A. microscope
B. petri dish
C. thermometer
D. triple-beam balance
Case Study
• How do independent and dependent
variables differ?
• How is scientific inquiry used in a reallife scientific investigation?
Case Study
• variable
• dependent variable
• independent variable
• constants
Biodiesel from Microalgae
• During the past few decades, scientists
have explored using protists to produce
biodiesel fuel.
• Protists are a group of microscopic
organisms that usually live in water or
moist environments.
Designing a Controlled Experiment
• Scientists use scientific inquiry to
investigate the use of protists to make
biodiesel.
• They design controlled experiments to
test their hypotheses.
• A controlled experiment is a scientific
investigation that tests how one variable
affects another.
Designing a Controlled Experiment
(cont.)
• A variable is any factor in an experiment
that can have more than one value.
• In controlled experiments, there are two
types of variables: dependent variables
and independent variables.
Designing a Controlled Experiment
(cont.)
• The dependent variable is the factor
measured or observed during an
experiment.
• The independent variable is the factor
that you want to test. It is changed by the
investigator to observe how it affects a
dependent variable.
Designing a Controlled Experiment
(cont.)
How do independent and
dependent variables differ?
Designing a Controlled Experiment
(cont.)
Constants are the factors in an
experiment that remain the same.
Designing a Controlled Experiment
• A controlled experiment has two
groups—an experimental group and
a control group.
(cont.)
• The experimental group is used to study
how a change in the independent
variable changes the dependent
variable.
• The control group contains the same
factors as the experimental group, but
the independent variable is not changed.
Biodiesel
• Rudolph Diesel invented the diesel
engine using peanut oil to demonstrate
how it worked.
• Oil-rich food crops, such as soybeans,
can be used as a source of biodiesel.
NPS Photo by Jim Peaco
Aquatic Species Program
• In the late 1970s, the U.S. Department
of Energy began funding its Aquatic
Species Program (ASP) to investigate
ways to remove air pollutants.
• The program’s focus shifted to using
microalgae to produce oils that could be
processed into biodiesel.
Which Microalgae?
• Microalgae are microscopic organisms
that live in marine or freshwater
environments, use photosynthesis, and
make sugar.
• Scientists collected and identified
promising microalgae species, focusing
on microalgae they predicted were more
resistant to changes in temperature and
salt content in water.
Oil Production in Microalgae
• Some studies suggested that starving
microalgae of nutrients, such as
nitrogen, could increase the amount of
oil they produced.
• Starving microalgae caused them to be
smaller, resulting in no overall increase
in oil production.
Outdoor Testing v. Bioreactors
• Three methods of growing microalgae
are examples of different hypotheses
being tested in controlled experiments.
• Open ponds are less expensive than
bioreactors for growing microalgae.
• Microalgae grown in plastic bags are
very expensive to harvest.
• Microalgae grow under controlled
conditions in glass bioreactors.
Why So Many Hypotheses?
According to Dr. Richard Sayre, a biofuel
researcher, all the ASP research was
based on forming hypotheses.
Increasing Oil Yield
Scientists from a biofuel company in
Washington State wondered if they could
increase microalgae oil production by
distributing light to all microalgae.
Bringing Light to Microalgae
• Data from experiments showed scientists
how microalgae in well-lit environments
grow compared to how microalgae grow
in dimmer environments.
• Scientists plan to take light to microalgae
instead of moving microalgae to light.
• Light rods and paddlewheels were both
used to bring light to microalgae.
Bringing Light to Microalgae (cont.)
Describe three ways in which
scientific inquiry was used in
this case study.
Why Grow Microalgae?
• In addition to growing microalgae for
biodiesel production, there are other
benefits of growing microalgae.
• Not only do microalgae produce
a valuable fuel, they also remove
pollutants from and add oxygen to the
atmosphere.
Are microalgae the future?
• The costs of growing microalgae and
extracting their oils are too high to
compete with petroleum-based diesel.
• The combined efforts of governmentfunded programs and commercial biofuel
companies might one day make
microalgae-based biodiesel and
affordable reality in the United States.
Which term describes a scientific
investigation that tests how one
variable affects another?
A. constants
B. control group
C. controlled experiment
D. experimental group
Which is a factor in an experiment
that remains the same?
A. constant
B. dependent variable
C. independent variable
D. variable
Which contains the same factors
as the experimental group, but
does not have the independent
variable changed?
A. constant
B. control group
C. controlled experiment
D. variable
Key Concept Summary
Chapter Review
Standardized Test Practice
The process of
scientific inquiry and
performing scientific
investigations can
provide answers to
questions about your
world.
Lesson 1: Understanding Science
• Scientific inquiry, also known as scientific methods,
is a collection of skills that scientists use in different
combinations to perform scientific investigations.
• Scientific investigations often result in new
technology, new materials, newly discovered objects
or events, or answers to questions.
• A scientist can help prevent bias in a scientific
investigation by taking random samples, doing blind
studies, repeating an experiment several times, and
keeping accurate and honest records.
Lesson 2: Measurement and
Scientific Tools
• Precision is a description of how similar or close
measurements are to each other. Accuracy is a
description of how close a measurement is to an
accepted value.
• Significant digits communicate the precision of the
tool used to make measurements.
• Life scientists use many tools, such as science
journals, microscopes, computers, magnifying
lenses, slides, and dissecting tools.
Lesson 3: Case Study: Biodiesel from
Microalgae
• The independent variable is a factor in an
experiment that is manipulated or changed by the
investigator to observe how it affects a dependent
variable. The dependent variable is the factor
measured or observed during an experiment.
• Scientific inquiry is used to gain information and find
solutions to real life problems and questions.
Which term refers to the
investigation and exploration of
natural events and of the new
information that results from those
investigations?
A. inference
B. reasoning
C. science
D. skepticism
Which term describes a logical
explanation of an observation
that is drawn from prior
knowledge or experience?
A. hypothesis
B. inference
C. prediction
D. scientific law
Which term describes how similar
or close measurements are to
each other?
A. accuracy
B. base unit
C. precision
D. significant digit
Which enables scientists to
observe small objects that cannot
be observed with just eyes?
A. compound light microscope
B. graduated cylinder
C. thermometer
D. triple-beam balance
Which term refers to the factor
that you test in an experiment?
A. constant
B. control group
C. dependent variable
D. independent variable
Which describes a pattern or an
event in nature that is always true?
A. critical thinking
B. hypothesis
C. scientific law
D. scientific theory
Which term describes a possible
explanation about an observation
that can be tested by scientific
investigations?
A. hypothesis
B. inference
C. observation
D. prediction
Which term refers to the digits in a
measurement that are known with
a certain degree of reliability?
A. base
B. constant
C. SI
D. significant
Which is used by scientists to
measure the volume of a liquid?
A. petri dish
B. microscope
C. graduated cylinder
D. computer
Which term refers to the factor
measured or observed during an
experiment?
A. constant
B. dependent variable
C. experimental group
D. independent variable