(Experimenting Terms)

How to Design an Experiment

It is an organized procedure for TESTING a hypothesis.

What is an

Experiment?

A process in which you test to see how one thing affects another thing.

It is a possible explanation for a problem based on what is known

and observed.

What is a

hypothesis?

It is much more than just an educated GUESS.

Your Hypothesis must be supported with logical thinking..

It is the factor in an experiment that is changed on purpose to see how

it affects something else.

What is the

Independent Variable?

If you are having a hard time identifying the Independent Variable in an experiment, just put yourself in the role of the scientist that did the

experiment and say, “The Independent Variable is the factor that I changed.”

The levels are simply the number of different changes that you will try.

What are Levels of Independent Variable?

EVERY experiment must have a minimum of TWO levels:

(1)The First level should be the Controlled level

(2)The second and beyond should be the Change(s) being tested

It is the factor in an experiment that is expected to change only after

the scientist changes the Independent Variable.

What is the

Dependent Variable?

• This is the part of the experiment that you are Measuring.

• So this means that it must be something that CAN BE measured.

Factors in an experiment that Do NOT change from one level to the next.

What are

Constants?

You are to ONLY change the Independent Variable and NOTHING ELSE!.

If you change more than one thing there is no

way to tell what factor caused the change.

It is the level of the experiment where the scientist DOES NOT introduce a change.

What is the

Control?

This level of the experiment is considered to be what

would happen under “Normal” conditions.

ALL Data from the other levels are compared to

the control data.

Repeating the experiment more than once for each level of the experiment will

make the DATA more reliable.

Why do a

Number of Trials?

The results of the trials should be averaged together to eliminate possible errors of data collection process.

Here’s an

Example

Retired professional soccer player, Landon Donovan wonders and then asks the following question:

“How does the air pressure of a soccer ball affect the distance it can be kicked?”

Because, research shows that more air will cause a soft object to become more firm which increase the affects of Newton’s 3rd law.

After doing some research, Landon decides to test the following Hypothesis:

If a soccer ball’s air pressure is increased, then the kicked distance of

the ball will also increase…What is the Independent Variable of his experiment?

The ball’s air pressure

What is the Dependent Variable of his experiment

(What is he measuring)?The distance kicked

He will test the following

Levels of Independent Variable

Level 1:Official PSI

8.7 PSI

Level 2:Slightly

higher PSI9.0 PSI

Level 3:Slightly

lower PSI8.0 PSI

Level 4:Extremely higher PSI15.0 PSI

Level 5:Extremely lower PSI2.4 PSI

He will run all five levels

the same wayAll test will take place in an indoor area. What will stay constant because of this testing location?

After watching a YouTube video,

he decides to build and use a machine to provide a consistent force to each ball

Kicking Machine Blueprints

He collects the following

DATALevel Trial 1 Trial 2 Trial 3 Average

 8.7 PSI 5.0000 m 5.1000 m 4.9000 m 5.0000 m

 9.0 PSI 5.5000 m 5.7000 m 5.9000 m 5.7000 m

 8 PSI 4.2000 m 4.8000 m 4.5000 m 4.5000 m

15 PSI 6.0000 m 6.2000 m 5.8000 m 6.0000 m

 2.4 PSI 0.2000 m 0.2000 m 0.2000 m 0.2000 m

Which Level Represents the Control?Level 1 – 8.7 PSI

Because it is at “Normal” PSI