Scientific Method Steps, descriptions, and examples *Answer the practice problems at the end of the notes.

1. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 1
Scientific Method

2. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 2
Scientific Method
The scientific method has these steps:
1. PROBLEM – Usually a question based on observations
2. RESEARCH THE PROBLEM
3. HYPOTHESIS – answer to the question
4. WRITE THE PROCEDURE – include materials and specific
procedure
5. PERFORM THE EXPERIMENT – experimental/variable group
and control group
6. COLLECT DATA and OBSERVATIONS - your observations;
pictures, tables, graphs, etc.; Quantitative or Qualitative
observations
7. ANALYZE DATA
8. CONCLUSION – “I/We therefore conclude that __________
because the data showed _____________ and that my/our
hypothesis is correct/wrong.”

3. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 3
Problem

4. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 4
What’s the difference?
 A HYPOTHESIS is a testable
prediction about a problem.
 A THEORY is an explanation backed
by results from repeated tests or
experiments.
 A LAW is a well-tested description of
how something in nature works.

5. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 5
ObservationsObservations
 GatheredGathered
through yourthrough your
sensessenses
 A scientistA scientist
noticesnotices
something insomething in
theirtheir naturalnatural
worldworld

6. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 6
Observations & QuestionsObservations & Questions
 AnAn exampleexample of anof an
observationobservation might bemight be
noticing that manynoticing that many
salamanders near a pondsalamanders near a pond
have curved, nothave curved, not
straight, tailsstraight, tails
 This might lead aThis might lead a
scientist toscientist to questionquestion
whywhy??

7. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 7
Research & Gather Information
 Find out what isFind out what is
already knownalready known
 Why is thisWhy is this
important?important?

8. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 8
HypothesisHypothesis
 A suggested solution toA suggested solution to
the problem.the problem.
 Must beMust be testabletestable
 SometimesSometimes written aswritten as If…If…
Then…Then… statementsstatements
 PredictsPredicts an outcomean outcome

9. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 9
HypothesisHypothesis
 AnAn example of aexample of a
hypothesishypothesis might bemight be
that the salamandersthat the salamanders
have curved tails due tohave curved tails due to
a pollutant in the moista pollutant in the moist
soil where they live.soil where they live.

10. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 10
ExperimentExperiment
 A procedureA procedure
toto testtest thethe
hypothesis.hypothesis.

11. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 11
Designing an ExperimentDesigning an Experiment
Experimental design :
Experimental group - goes through all the
steps of the experiment and is exposed
to the factor being tested.
Control group - goes through all the steps
of the experiment but is not exposed to
the factor being tested.

12. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 12
Controlled Laboratory Experiment ExampleControlled Laboratory Experiment Example

13. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 13
VariablesVariables
 Independent variableIndependent variable
the factor that the
experimenter “I”
changes
 Dependent variableDependent variable
what thewhat the
experimenterexperimenter observes
or measures as a
result of what was
changed

14. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 14
The Control VariableThe Control Variable
 The experimenter makes aThe experimenter makes a
special effort to keepspecial effort to keep otherother
factors constantfactors constant so thatso that
they will not effect thethey will not effect the
outcome.outcome.
 Those factors are calledThose factors are called
control variables.control variables.

15. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 15
What is the Purpose of aWhat is the Purpose of a
Control?Control?
Controls are NOT being
tested
Controls are used for
COMPARISON

16. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 16
Example of Controls &Example of Controls &
VariablesVariables
 For example, suppose you want to figure out
the fastest route to walk home from school.
 You will try several different routes and time
how long it takes you to get home by each
one.
 Since you are only interested in finding a
route that is fastest for you, you will do the
walking yourself.

17. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 17
What are the Variables in YourWhat are the Variables in Your
Experiment?Experiment?
 Varying the route is theVarying the route is the
independent variableindependent variable
 The time it takes is theThe time it takes is the
dependent variabledependent variable
 Keeping the same walkerKeeping the same walker
throughout makes the walker athroughout makes the walker a
control variable.control variable.

18. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 18
DataData
 Based on Observations
Observations are based on the five
senses
See, hear, feel, taste, smell

19. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 19
2 Types of Data
 Quantitative: measurements
(think: quantity)
 Qualitative: only
observational but not
measureable

20. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 20
Data
 Inferences DO NOT
belong in observations
 Inferences are opinions,
judgements, ideas or
thoughts about
observations

21. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 21
DataData
 Must be
organized
 Can be
organized into
charts,
tables, or
graphs

22. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 22
ConclusionConclusion
 A ConclusionConclusion is a
statement based on the
data of the experiment.
 The conclusion may or
may not support the
hypothesis.
 The answer to the
hypothesis based on
the data obtained
from the experiment

23. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 23
Write the following in your notes:
 Identify the following for each scenario
 (1st
or Smithers scenario is an Example):
1. Problem
2. Hypothesis
3. Control Group
4. Experimental Group
5. Independent Variable
6. Dependent Variable
7. Constants
8. What should the conclusion be?
9. Is the data quantitative or qualitative?

24. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 24
 Smithers thinks that juice
will increase the productivity
of workers. He creates two
groups of 50 workers each
and assigns each group the
same task (in this case,
they're supposed to staple a
set of papers). Group A is
given the juice to drink
while they work. Group B is
not given the juice. After an
hour, Smithers counts how
many stacks of papers each
group has made. Group A
made 1,587 stacks, Group B
made 2,113 stacks.

25. Smithers Scenario Answers
1. Problem
Will drinking juice increase the worker’s productivity?
2. Hypothesis
Drinking juice will increase productivity
3. Control Group:
Group B
4. Experimental Group:
Group A
5. Independent Variable:
The Juice
6. Dependent Variable:
Increase or Decrease Productivity
7. Constants:
# of workers (both 50 workers and task (stapling papers)
8. What should the conclusion be?
That the juice was not effective in increasing productivity
9. Is the data quantitative or qualitative?
Quantitative
Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display.

26. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 26
 Homer notices that his
shower is covered in a
strange green slime. His
friend Barney tells him
that coconut juice will get
rid of the green slime.
Homer decides to check
this out by spraying half
of the shower with
coconut juice. He sprays
the other half of the
shower with water. After
3 days of "treatment"
there is no change in the
appearance of the green
slime on either side of
the shower.

27. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 27
 Bart believes that mice exposed
to microwave rays will become
extra strong. He decides to
perform this experiment by
placing 10 mice in a microwave
for 10 seconds. He compared
these 10 mice to another 10
mice that had not been
exposed. His test consisted of a
heavy block of wood that
blocked the mouse food. he
found that 8 out of 10 of the
microwaved mice were able to
push the block away. 7 out of
10 of the non-microwaved mice
were able to do the same.

28. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 28
 Krusty was told that a certain
itching powder was the newest
best thing on the market, it
even claims to cause 50%
longer lasting itches. Interested
in this product, he buys the
itching powder and compares it
to his usual product. One test
subject (A) is sprinkled with the
original itching powder, and
another test subject (B) was
sprinkled with the experimental
itching powder. Subject A
reported having itches for 30
minutes. Subject B reported to
have itches for 45 minutes.

29. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 29
The Strange Case of BeriBeri
 In 1887 a strange nerve
disease attacked the
people in the Dutch East
Indies. The disease was
beriberi. Symptoms
included weakness and
loss of appetite, victims
often died of heart
failure. Scientists thought
the disease might be
caused by bacteria. They
injected chickens with
bacteria from the patients
blood. The injected
chickens became sick.
However, so did a group
of chickens that were not
injected with bacteria.

30. Copyright@ McGraw-Hill
Companies, Inc. Permission
required for reproduction or
display. 30
New observation/hypothesis
 One of the scientists,
Dr. Eijkman, noticed
something. Before the
experiment, all the
chickens had eaten
whole-grain rice, but
during the
experiment, the
chickens were fed
polished rice. Dr.
Eijkman researched
this interesting case.
he found that polished
rice lacked thiamine, a
vitamin necessary for
good health.