Unit 1, Lesson 1.8 - The Scientific Method (Part Two)

The Scientific
Method
Part Two: Unit One, Lesson 2.2
By Margielene D. Judan

LESSON OUTLINE
 Throwback: The Scientific Method
 Testing the Hypothesis
 Experimentation
 Three Types of Experiments
 Understanding Experimental Variables

THROWBACK: THE SCIENTIFIC METHOD
It is a systematic way of investigation in order to
solve a problem.

THROWBACK: BASIC STEPS OF THE
SCIENTIFIC METHOD
1. State the problem or ask questions.
(Observation)
2. Form a hypothesis.
3. Test your hypothesis by experimentation.
4. Record and analyze data.
5. State a conclusion.
6. Report your findings.

The Scientific
Method Flowchart
(always use this
chart when making
scientific
investigations)

TESTING THE HYPOTHESIS
To test the hypothesis, the experiment should be a
fair test (you change only one variable at a time
while keeping other conditions the same).
To insure that your experiment is a fair test, you must
change only one factor at a time while keeping all
other conditions the same.
Control group- the part of the experiment without
the variables being tested
Experimental group- the part that contains the
variable being tested.

EXPERIMENTATION
Basically a test of hypothesis

When experimenting, you must also
make predictions.
Predictions are forecasts of future events based on
past observations.

THREE TYPES OF EXPERIMENT
1. Controlled experiment
2. Natural experiment
3. Field experiment

Controlled Experiments
an experiment or trial that uses controls, usually
separating the subjects into one or
more control groups and experimental groups.
A variable is a characteristic, number, or
quantity that increases or decreases over time. It
is anything that you can change or control in an
experiment.
There are three kinds of variables: (next slide)

3 Kinds of Variables
Controlled variable- constant and unchanged
in an experiment.
Independent variable- factors which you
change or alter during the experiment
Dependent variable- response to an
independent variable

Natural or Quasi-Experiments
No variable is being changed or altered
Rely solely on observations to determine the factors
which caused the phenomenon
(ex. Astronomy. To prove that the earth is round, you
don’t need to change any variables. You cannot
change the amount of sunlight, nor the shape of the
earth. You just need to determine or identify the
factors which caused the phenomenon.)

Field Experiments
applies the scientific method to experimentally
examine an intervention in the real world rather
than in the laboratory
Often used in social sciences such as
psychology, economics, and political science
Field- outside the lab/not conducted inside a
laboratory

Example: (refer to your book p. 31)
A group of student tested the effect of fertilizer on
the growth of plants. They used six plants that are 15
cm tall. They grouped the plants into two groups: A
and B. They watered the plants in group A with 200
mL of plain water and in group B with 200 mL of
fertilizer solution. They watered the plants twice a
week with the same amount of water and exposed
them to the same amount of sunlight. After three
weeks, they measured the growth of the plants in
each group.

Example: (refer to your book p. 31)
Treatment:
200 mL of plain water twice
a week for 3 weeks
18 cm tall 32 cm tall
The following are the results:
Group A Group B
Treatment:
200 mL of fertilizer solution
twice a week for 3 weeks

Question 1: Which is the experimental
and control group?
Treatment:
a week for 3 weeks
Group A Group B
Treatment:

Answer: Group A- control group
Group B- experimental group
Treatment:
a week for 3 weeks
Group A Group B
Treatment:

Control group- the part of the experiment
without the variables being tested
(Group A has no variables tested. It is only
watered with plain water. But a control
group is important for us to be able to
compare the results with the experimental
group.)
Experimental group- the part that contains
the variable being tested.
(Group B was watered with fertilizer [the
variable being tested])

Question 2: Which is the controlled,
independent, and dependent variables?
Treatment:
a week for 3 weeks
Group A Group B
Treatment:

Answers:
Controlled variable
amount of sunlight, kind of plant, initial
size of plant
Independent variable
-amount of fertilizer
Dependent variable
-growth of plant

Answer:
Controlled variable
amount of sunlight, kind of plant, initial size
of plant
Controlled variable- constant and
unchanged in an experiment.
Both groups are have the same amount of
sunlight, kind of plant, and have the same
size at start of the experiment.

Answer:
Independent variable
-amount of fertilizer
Independent variable- factors which you
change or alter during the experiment
The difference between the experiment is
that we used a fertilizer solution instead of
water on group B.

Answer:
Dependent variable
-growth of plant
Dependent variable- response to an
independent variable
As a result to the fertilizer (independent
variable), there is a difference in their
growth size.

Take note of these following terms. You
need to be able to identify and differentiate
each. They will always appear in our
experiments and lab works.
Experimental and control group
Controlled, independent, and dependent
variables
A fair test

Laboratory Tomorrow/next meeting (by
group): Bring the following
Three 250 ml transparent cups
Cold, normal, and hot water
Dropper
Ink
Two Stopwatches (1 is enough)
Black, Blue, and Red Ballpen
Ruler

Unit 1, Lesson 1.8 - The Scientific Method (Part Two)

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Unit 1, Lesson 1.8 - The Scientific Method (Part Two)