Lesson Overview

1
Lesson Overview

• 1.1 What Is Science?

2
What Science Is and Is Not

• What are the goals of science?
• One goal of science is to provide natural
  explanations for events in the natural world.
  Science also aims to use those explanations to
  understand patterns in nature and to make useful
  predictions about natural events.

3
Science as a Way of Knowing

• Science is an organized way of gathering and
  analyzing evidence about the natural world.
• ExamplesCan use science to answer questions
  about how whales
• - communicate
• -how far they travel
• -how they are affected by environmental changes.

Scientists - collect and organize information
- looking for patterns and connections among
events. -propose explanations that are based on
evidence, not belief. -test those
explanations. SCIENCE IS A
PROCESS NOT A THING!
4
Scientific Methodology The Heart of Science

• What procedures are at the core of scientific
  methodology?
• Scientific methodology involves observing and
  asking questions, making inferences and forming
  hypotheses, conducting controlled experiments,
  collecting and analyzing data, and drawing
  conclusions.

5

• Mystery Worms
• A teacher collected some beetles from a rotting
  log and placed them in
• a container of dry oatmeal in her classroom. She
  kept the box covered
• with a light cloth so that the beetles could not
  escape. She also asked
• one of her students to add potato and apple
  pieces once a week to
• provide food and moisture for the beetles. After
  several weeks, the student reported that there
  were some strange-looking, wormlike organisms in
  the container.
• 1. Formulate a hypothesis that might explain the
  presence of the
• worms in the container.
• 2. How could you test your hypothesis?
• 3. Identify the variables in your proposed
  experiment. Identify the
• control in your proposed experiment.
• 4. What data would you collect during your
  experiment?

6
Observing and Asking Questions

• Scientific investigations begin with
  observation, the act of noticing and describing
  events or processes in a careful, orderly way.
• What could a researcher observe from the picture
  below?
• Marsh grass grows taller in some places than
  others.
• What question could you ask based on this
  observation?
• Why do marsh grasses grow to different heights
  in different places?

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Inferring and Forming a Hypothesis

• Inferences or logical interpretations based on
  what is already known.
• Hypothesis, or a scientific explanation for a
  set of observations that can be tested in ways
  that support or reject it.
• Give an example of an inference, hypothesis?

Inferred that something limits grass growth in
some places. Based on their knowledge of salt
marshes, they hypothesized that marsh grass
growth is limited by available nitrogen.
8
Designing Controlled Experiments

• A controlled experiment is one in which only one
  variable is changed.
• -All other variables should be kept unchanged, or
  controlled.
• Designing an experiment
• Variables various factors that can change
• Examplestemperature, light, time, and
  availability of nutrients.
• Why is it important to control variables?
• It is important to control variables because if
  several variables are changed in the experiment,
  researchers cant easily tell which variable is
  responsible for any results they observe.

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Controlling Variables

• Independent variable The variable that is
  deliberately changed is called the (also called
  the manipulated variable).
• Dependent variable The variable that is
  observed and that changes in response (also
  called the responding variable).

A control group is exposed to the same conditions
as the experimental group except for one
independent variable.
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Designing Controlled Experiments

• Example of controls
• -similar plots of marsh grass
• -similar plant density
• -soil type
• -input of freshwater
• -height above average tide level.
• What is the independent variable in this
  experiment?
• What is the dependent variable?

• Nitrogen fertilizer (the independent variable)
• the growth of marsh grass (the dependent
  variable)

11
Collecting and Analyzing Data

• DATA experimental observations and information.
• Two main types of data
• - quantitative dataare numbers obtained by
  counting or measuring
• - qualitative dataare descriptive and involve
  characteristics that cannot usually be counted

What type of data can we collect that is
quantitative?
number of plants per plot, plant sizes, and
growth rates
What type of data can we collect that is
qualitative?
notes about foreign objects in the plots, or
whether the grass was growing upright or sideways
12
Research Tools
Scientists choose appropriate tools for
collecting and analyzing data. Tools include
-simple devices such as metersticks -sophisticat
ed equipment such as machines that measure
nitrogen content -charts and graphs that help
scientists organize their data.

• This graph shows how grass height changed over
  time.

13
Sources of Error

• Researchers must be careful to avoid errors in
  data collection and analysis.
• Examples
• -Tools used to measure the size and weight of
  marsh grasses, for example, have limited
  accuracy.
• The larger the sample size, the more reliably
  researchers can analyze variation and evaluate
  differences between experimental and control
  groups.

14
Drawing Conclusions
Scientists use experimental data as evidence to
support, refute, or revise the hypothesis being
tested, and to draw a valid conclusion. Wha
t conclusion could you make from this experiment?

• Analysis showed that marsh grasses grew taller
  than controls by adding nitrogen.

15
Drawing Conclusions

• What happens if new data is presented that
  doesnt fit the conclusion?
• -Revise original hypothesis
• -Make new predictions
• -Design new experiments
• This process may be repeated several times.

16
Scientific Theories

• What is a scientific theory?
• In science, the word theory applies to a
  well-tested explanation that unifies a broad
  range of observations and hypotheses and that
  enables scientists to make accurate predictions
  about new situations.

17
Scientific Theories

• A scientific theory
• -applies to a well-tested explanation that
  unifies a broad range of observations and
  hypotheses
• - it enables scientists to make accurate
  predictions about new situations.
• -has been thoroughly tested and supported by
  many lines of evidence may become the dominant
  view among the majority of scientists.
• No theory is considered absolute truth. Science
  is always changing as new evidence is uncovered,
  a theory may be revised or replaced by a more
  useful explanation.

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When Experiments Are Not Possible

• It is not always possible to test a hypothesis
  with an experiment.
• -Observational Studies
• Example
• Animal behavior researchers might want to learn
  how animal groups interact in the wild by making
  field observations that disturb the animals as
  little as possible.
• -Ethical Issues
• Example
• Medical researchers who suspect that a chemical
  causes cancer, for example, would search for
  volunteers who have already been exposed to the
  chemical and compare them to people who have not
  been exposed to the chemical.