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8th GRADE SCIENCE
STRAND 1THE 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!!!!!!!!!!!!!!