Transcript Chapter 2 - Cherokee County Schools

Chapter 2: Tools of
Environmental Science
Cherokee High School
Environmental Science
Mrs. Toner
The Scientific Method
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Also known as the experimental method.
It is a series of steps that scientists all over the
world use to identify and answer questions.
The first step is observation – information we
gather using our senses (sight, touch, hearing,
smell).
What kinds of tools do scientists use to observe?
 Observations can be in the form of descriptions,
drawings, photographs, and measurements.
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Tools Scientists Use to Observe
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The Scientific Method (continued)
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Observations lead to questions. To answer a
specific question, a scientist may form a…..
Hypothesis – a testable idea which leads to an
experiment (or scientific investigation).
A hypothesis is more than a guess! Often, it is
based on what you already know.
 See handout on Dwarf Wedge Mussels.
 To test their hypothesis, the students made a
prediction which is a logical statement about what
will happen if the hypothesis is correct.
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The Scientific Method (continued)
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Experiment – a procedure designed to test a
hypothesis under controlled conditions.
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Scientists usually study two groups at a time:
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Experiments must be designed to pinpoint cause-and-effect
relationships. So, a single variable is tested and a control is
used.
The group that receives the experimental treatment is called
the experimental group.
The group that doesn’t receive the experimental treatment is
called the control group.
The variable is the single factor of interest and it is the
only difference between the experimental group and the
control group.
The Scientific Method (continued)
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Collecting data – the information a scientist
gathers during an experiment which is usually in
numerical form.
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Scientists organize their data into tables, charts,
and/or graphs. This makes it easier for them to
communicate their findings to others.
The Scientific Method (continued)
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Reaching a conclusion –
Scientists study their data to determine the results
from their experiment.
 Scientists compare the outcome of their experiment
to their prediction.
 A conclusion is made.
 Often, experiments are repeated to see if the results
are reliable.
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The Scientific Method:
Observation
Question
Analyze Data
Conclusion
Scientific Habits of Mind
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Good scientists share some key “habits of mind” or
ways of approaching or thinking about things:
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Curiosity – a genuine interest in a subject leads to wanting to
learn more about it.
The Habit of Skepticism – not believing everything you are
told.
Openness to New Ideas – keeping an open mind as to how
the world works.
Intellectual Honesty - being honest about your results
Imagination and Creativity – ability to conceive new ideas, see
patterns that others cannot, or to imagine things others cannot.
What’s the difference between a
hypothesis and a prediction?
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A hypothesis is a testable idea that leads to an
experiment.
A prediction is a logical statement about what
will happen if the hypothesis is correct.
For example, the Keene High School students
hypothesized that phosphate fertilizers from lawns
were washing into the river and killing the mussels.
 The students may have predicted that mussels will
die when exposed to high levels of phosphate in the
water.
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Making Correlations
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Scientists study questions by doing experiments. But what
if an experiment can’t be done?
Scientists can test predictions by examining correlations –
associations between two or more events.
The width of rings in a tree trunk indicate the amount of
rainfall the tree received in a given year. Trees produce
wide rings in rainy years and narrow rings in dry years.
Scientists used this information to investigate why most of
the first settlers at Jamestown, VA died.
The rings of very old trees on the Virginia coast indicate
that the Jamestown colony was founded during one of the
worst droughts ever recorded. The settlers most likely died
from starvation as a result of not being able to farm.
Rings of a Tree Trunk Can be
Used to Make Correlations:
Students at Keene High School Study Dwarf
Wedge Mussels
1. The students have observed
that____________.
2. The students also have observed
that the______ is __________.
3. These observations prompted the
students to take the next step in
the experimental method __________ a ____________.
4. What two trends did the students
notice?
5. When students tested the water,
what did they find?
6. What are phosphates?
7. How might phosphates end up in
the water?
8. What was the prediction the
students made?
9. What is the difference between a
hypothesis and a prediction?
Read the “Case Study” on
page 35 and answer the
following questions:
1. Explain what students placed into
each of the two tanks.
2. What 4 things were to be constant
(identical) when setting the tanks
up?
3. What did the students do to the
experimental group?
4. What did they do to the control
group?
5. What does replication mean and
how could the students replicate
their experiment?
Review of Chapter 2, Section 1:
1. Describe the steps of the experimental method.
2. Name three scientific habits of mind and explain their
importance.
3. Explain why a hypothesis is not just a guess.
Vocabulary Words:
observation
hypothesis
prediction
experiment
variable
experimental group
control group
data
correlation
Statistics and Models
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Scientists generate a lot of data which needs to
be organized.
Statistics is the collection and organization of
data that are in the form of numbers.
Used to summarize, characterize, analyze and
compare data.
 Some terms – mean, distribution, probability, sample
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What’s the Average?
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The mean is the number obtained by adding the
data for a characteristic and dividing this sum by
the number of individuals (average).
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The mean provides a single measure for a given
characteristic of a population.
Find the mean for the following data set:
12, 25, 32, 6
 12 + 25 + 32 + 6 = 75
 75/4 = 18.75
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The Distribution
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A distribution is the relative arrangement of the
members of a statistical population (see pg. 41,
figure 9).
The lengths of the individuals are arranged between
15 and 50.
 The overall shape of the bars is also part of the
distribution.
 Notice the bell-shaped curve. A bell-shaped curve
represents a normal distribution.
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What is the Probability
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Probability – the chance that something will happen.
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What’s the probability that if you toss a coin it will come up
heads?
Usually expressed as a decimal between 0 and 1:
Suppose a quarter comes up heads 7 out of 10 times.
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7/10 = 0.7 Is this 50/50? No! What’s the problem? The problem is that
the sample size is too small to give an accurate result.
Sample – a group of individuals or events selected to
represent the population.
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What’s the sample size if you toss a coin 10 times?
What’s the sample size if you toss the coin 1,000 times? We are
almost certain to see heads 50% of the time and tails 50% of the
time with a sample size this large.
Risk
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Risk – the probability of an unwanted outcome.
Example - 60% chance of rain today. What is
the risk that it will rain?
Example – if you have a 1 in 4 chance of failing
a class, the risk of failing is ¼, or 0.25.
Models
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Models are representations of objects or systems.
Physical Models
 Graphical Models
 Conceptual Models
 Mathematical Models
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Physical Models
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Physical Models are three-dimensional models
you can touch.
The most useful models teach scientists
something new and help to further other
discoveries.
Example – the structure of DNA (pg 44, figure
12).
Graphical Models
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Maps and charts (pg 44, fig. 13)
Graphical models are used to show things like
the position of stars, the amount of forest cover
in an area, or the depth of water along a coast.
Conceptual Model
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A conceptual model – a verbal or graphical
explanation of how a system works or is
organized.
A flow chart diagram is an example.
See page 45, fig. 14.
Mathematical Models
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A mathematical model is one or more equations
that represents the way a system works.
Chapt. 2, Section 2 Vocabulary (text
book pages 40-46)
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Statistics
Mean
Distribution
Probability
Sample
Risk
Model
Physical model
Graphical model
Conceptual model
Mathematical model
2.3 – Making Informed Decisions
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Scientific research is the first step to solving
environmental problems.
Many factors must be considered before
decisions can be made about solutions:
How will people’s lives be affected?
 How much will it cost?
 Is the solution ethical?
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Questions like the ones above require an
examination of values.
What are values?
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Values are moral principles we consider
important.
Which values should influence decisions we
make about our environment?
Economic – the gain or loss of money or jobs
 Environmental – the protection of natural resources
 Ethical/moral – what is right or wrong
 Health – the maintenance of human wellbeing
 Social/cultural – maintaining human communities,
their values and traditions
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An Environmental DecisionMaking Model
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A decision-making model is a conceptual
model that provides a systematic process for
making decisions.
Gather
Information
Consider
Values
Explore
Consequences
Make a
Decision