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!!!!!!!!!!!!!!