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8 GRADE SCIENCE
STRAND 1
THE NATURE OF SCIENCE
NS 1.8.1 – NS 1.8.3
THE SCIENTIFIC METHOD

The Scientific Method is a series of planned steps used by
scientists to solve problems. These are the steps:
 1. Ask a question or determine a problem.
 2. Make a Hypothesis.
 3. Gather data and test your hypothesis.
 4. Analyze the results of your testing.
 5. Draw a conclusion.
BIGFOOT!
A Game and Fish officer in Little Rock
received a phone call from a person in
northwest Arkansas, claiming he had
evidence of a “Bigfoot” sighting there.
 The caller stated they had a plaster cast
footprint, a sample of weird looking hair
they found on a barbed wire fence, an
actual picture of “Bigfoot”, and, they had an
eye-witness.

BIGFOOT

Based on the data the officer gathered over
the phone, he can make his HYPOTHESIS.
 I THINK THERE IS A “BIGFOOT” IN
NORTHWEST ARKANSAS.
 Now what does the officer have to do?
 Go up there and gather the evidence.
THEN…
 Test the evidence!
ACTUAL PICTURE
HAIR SAMPLE
PLASTER CAST OF FOOTPRINT
BIGFOOT
The officer gathered these 3 pieces of data. The
eyewitness lived a few miles up in the hills, so he
would save him for last.
 He sent the picture to a photo lab to be analyzed.
 He sent the hair sample to a lab to be analyzed.
 He decided to “stake out” the area where the
footprint was located.

BIGFOOT
He went to the area dressed in his camo, and hid in
the bushes.
 After several hours he heard a loud THUMP!
 Then several seconds later another THUMP! Then
another and another, it was getting closer.
 The officer saw a man who had a long metal pole
with a metal cut out of a huge foot on the end of it.
The man was slamming the foot into the ground,
making footprints.

BIGFOOT
The officer stepped out of the bushes and
confronted him.
 After questioning, the man finally confessed
that he had a whiskey still hid in the area,
and he thought that if people thought there
was a bigfoot monster in the area, they would
be scared and stay away so he could make his
whiskey.

BIGFOOT
A day later, results from the hair sample and
picture came back.
 The hair sample was that of a north
American black bear.
 The picture was blown up 200 times, and a
zipper could be seen in the back of it.

BIGFOOT

The officer still had his eye-witness to check
out. He drove 3 miles up the old dirt road to
talk to the man.
BIGFOOT

His dogs met him at the
door!
BIGFOOT
When the man came
out, he was drunk as a
skunk, and told him he
had seen bigfoot, pink
elephants, and flying
saucers too!

BIGFOOT

What at first seemed liked a good hypothesis,
turned out to be false, but ONLY after
testing the evidence.
 He now had to make his conclusion….
 THERE IS NOT A BIGFOOT IN
NORTHWEST ARKANSAS!
VOCABULARY
1. CONTROL – In an experiment, the standard for comparison.
 2. VARIABLE – Measurable factor, characteristic, or attribute of an individual or a
system.
 3. EMPIRICAL EVIDENCE – Data that can be detected, observed, or measured.
 4. HYPOTHESIS – An “educated guess”. An explanation for a question or a problem
that can be formally tested.
 5. THEORY – A hypothesis that has been tested many, many times by different
scientists, and the results turn out the same.

VOCABULARY


6. SCIENTIFIC LAW - A descriptive generalization about how some aspect of the
natural world behaves. A theory that has been tested over and over by many
scientists, and is considered a “fact” of nature.
 7. EXPERIMENTAL DESIGN – The design of a suitable experiment to test a
hypothesis.
8. DEPENDENT VARIABLE – Factor being measured in an experiment, found on the
vertical or Y-axis on a graph.
 9. INDEPENDENT VARIABLE – The one factor changed in an experiment,
represented on the horizontal or X-axis on a graph.
VOCABULARY

10. SCIENTIFIC METHOD – A series of problem solving
procedures used by scientists.
EXPERIMENTS
Coach Bales thinks he has come up with a “SUPER
DUPER GROWTH PILL”
 His HYPOTHESIS (educated guess) is “I believe my super
duper growth pill will increase the size of a rat over a
period of time”
 His empirical evidence will be:
 2 rats from the same litter, as close in size and weight as he
can get.
 Each rat will get the same kind of food and water, also in
same amounts.
 1 rat will be given the “SUPER DUPER GROWTH PILL”

GROWTH PILL EXPERIMENT
Rat 1
This rat will not be
given the pill.
 He will be the
CONTROL, the
standard for
comparison in the
experiment.


GROWTH PILL EXPERIMENT
Rat 2
Rat 2 will get the SUPER
DUPER GROWTH PILL!
 This will be the
VARIABLE, or the
changeable factor of the
experiment.
It is very important in an
experiment that you only
test one variable at a time.



GROWTH PILL EXPERIMENT
Coach Bales will give each rat the same
amount of food and water at the same time
each day.
 Only rat 2 will get the growth pill.
 He will be compared to rat one to see if he
grows more or not.
 After 2 weeks……..

GROWTH PILL EXPERIMENT
Based on the evidence that the rat given the
growth pill did in fact get bigger in size,
Coach Bales can now form a theory, a
hypothesis that has been tested.
 His theory though, must be tested many
more times by many different scientists
before it can be accepted as a “scientific law”
or a fact of nature.

SOMETIMES, EXPERIMENTS
CAN BE BAD!!!!!!!!!!!!!!