### HYPOTHESIS AND VARIABLES

Step 3: Form a Hypothesis  Hypothesis- a testable explanation of an observation.

 A hypothesis is NOT just an educated guess about what you think will happen. It must be able to be tested!

Step 3: Form a Hypothesis  We write the hypothesis in an

If-Then statement

ex:

If

the amount of fertilizer is

then

the height of the plant increased, will increase.

Variables & Controls  A variable is anything that changes in a scientific experiment.

 The control is what you use to compare the results to in the end of the experiment.

There are 2 types of variables:  Independent  Dependent

Step 3: Form a Hypothesis  The Independent Variable goes after the “If” I.V.

If

the amount of fertilizer is increased,

then

the height of the plant will increase.

Step 3: Form a Hypothesis  The Dependent Variable goes after the “Then”

If

the amount of fertilizer is increased,

then

the height of the plant will increase. D.V.

Now You Try:  If you spend more time studying, then your grade will improve.

  Independent Variable = Dependent Variable =

Now You Try:  If you spend more time studying, then your grade will improve.

  Independent Variable = studying amount of time spent Dependent Variable = grade

Now You Try:  If the temperature of the room is increased, then the bacteria will grow faster.

  Independent Variable = Dependent Variable =

Now You Try:  If the temperature of the room is increased, then the bacteria will grow faster.

  Independent Variable = temperature of room Dependent Variable = bacterial growth

Variables & Controls  A variable is anything that changes in a scientific experiment.

 The control is what you use to compare the results to in the end of the experiment.

2 Types of variables:  Independent Variable: What you change.

Dependent Variable: What changes because of the Independent Variable.

2 Types of variables:  Independent Variable: Cause  Dependent Variable: Effect

Independent Variable  Independent Variable: What you change.

 Cause  a.k.a Manipulated Variable  Graphed on x axis

Dependent Variable  Dependent Variable: What changes because of the Independent Variable.

 Effect  a.k.a Responding Variable  Graphed on y axis

Independent Variable vs. Dependent Variable

Also Known As: Results: Independent Variable

Manipulated Variable Cause

Dependent Variable

Responding Variable Effect

On a graph:

X axis Y axis

After all of the data from the experiment is collected, then its time to organize the data.

Step 6: Organize your data  Put your data into a data table

Independent Variable __________(unit) Levels Dependent Variable _______________ (unit) Trial 1 Trail 2 Trail 3 mean range

Step 6: Organize your data  Make the data table into a graph

GRAPHS make it EASIER to see patterns in the data!

Step 6: Organize your data  How do you know what goes on each

axis

of the graph?

Step 6: Organize your data  DRY MIX  Dependent Variable = Responding Variable = Y axis  Manipulated Variable = Independent Variable = X axis

Parts of a graph Y Axis X Axis

Parts of a graph Y Axis (Dependent Variable) X Axis (Independent Variable)

Graphing: DRY MIX

Independent Variable

Any Questions????