Chapter 1
Section 2 Scientific Methods
Bellringer
Complete these two tasks:
1. Describe an advertisement that cites research
results.
2. Answer this question: Why is it important for
scientists to write reports about their findings?
Write your answers in your science journal.
Chapter 1
Section 2 Scientific Methods
What You Will Learn
• Scientists ask questions, make observations,
form hypotheses, test hypotheses, analyze
results, and draw conclusions.
• Scientists communicate their steps and results
from investigations in written reports and oral
presentations.
Chapter 1
Section 2 Scientific Methods
What are Scientific Methods?
• Scientific Methods are the ways in which scientists
follow steps to answer questions and solve
problems.
• All life scientists share a curiosity about the natural
world and similar methods to investigate it.
• Scientists may use the same steps in their
investigations, but not always in the same order.
Chapter 1
Section 2 Scientific Methods
Chapter 1
Section 2 Scientific Methods
Ask a Question
• An observation may be hard to explain or
out of the ordinary.
• Such an observation can lead to a question.
• Looking for answers may lead to more
observations and more questions.
Chapter 1
Section 2 Scientific Methods
Make Observations
• Observations must be made with great care
and attention to details.
• Observations are only useful if they are
accurately made and recorded.
• Records of observations include
measurements, tables, photographs, and
written descriptions.
Chapter 1
Section 2 Scientific Methods
Make Observations, continued
• Any information gathered through the
senses is an observation.
• Some typical observations include
measurements of length, volume, time,
speed, or temperature.
• Observations can describe the color, shape,
or behavior of an organism.
Chapter 1
Section 2 Scientific Methods
Form a Hypothesis
• After asking questions and making
observations, scientists may form a
hypothesis. Sometimes observations lead
to several hypotheses.
• A hypothesis is a possible explanation or
answer to a question.
• A hypothesis needs to be testable.
Chapter 1
Section 2 Scientific Methods
Form a Hypothesis, continued
• After forming a hypothesis, a scientist
usually makes a prediction.
• The prediction is usually stated in an ifthen format.
• The prediction is used to set up an
experiment to test the hypothesis.
Chapter 1
Section 2 Scientific Methods
Test the Hypothesis
• Scientists conduct controlled experiments to
test their hypotheses.
• A controlled experiment tests only one factor
at a time and consists of a control group and
one or more experimental groups.
• A factor is anything in an experiment that can
influence the experiment’s outcome.
Chapter 1
Section 2 Scientific Methods
Test the Hypothesis, continued
• In a controlled experiment, every factor
must be kept the same except for the one
factor being tested.
• The one factor that is tested, or changed, in
an experiment is called the variable.
Chapter 1
Section 2 Scientific Methods
Test the Hypothesis, continued
• The group of test subjects that includes the
variable is called the experimental group.
The group that does not change is called
the control group.
• The only difference between the control
group and the experimental group is the
variable being tested.
Chapter 1
Section 2 Scientific Methods
Test the Hypothesis, continued
Chapter 1
Section 2 Scientific Methods
Test the Hypothesis, continued
• In addition to carefully controlled factors, a
good experiment should test many
individuals.
• When scientists test many individuals, and
repeat the experiment several times, the
results are more certain.
Chapter 1
Section 2 Scientific Methods
Test the Hypothesis, continued
Chapter 1
Section 2 Scientific Methods
Analyze the Results
• After scientists finish their tests, they must
analyze the results.
• Data are often organized into graphs or
tables.
• This helps scientists focus on the effects of
the variable being tested.
Chapter 1
Section 2 Scientific Methods
Draw Conclusions
• After scientists analyze the results, they can
draw conclusions about whether the results
support their hypotheses.
• When the results do not support the original
hypothesis, scientists still learn from the
experiment.
• A single experiment rarely answers a complex
question. Each experiment builds on prior
knowledge, and suggests areas of future study.
Chapter 1
Section 2 Scientific Methods
Communicate Results
• After scientists complete an investigation, they
communicate their methods, results, and
conclusions.
• By communicating with written reports and oral
presentations, scientists allow other scientists to
repeat their work to see if the results are the same.
• Sharing information may also help other scientists
with their own investigations. In this way, the
scientific methods help strengthen our knowledge.