What is a Variable?

Types of Variables

• Independent Variable (a.k.a. “Manipulated Variable” or “Test

Variable”)

The condition that will be changed by the scientist in an experiment.

• Dependant Variable (a.k.a. “Responding Variable”)

The condition(s) that will be measured in an experiment; these are the experimental data.

Types of Variables

• The Controls/Constants (a.k.a. “Controlled Variables)

The conditions that are kept the same (unchanged) in an experiment.

Typically, several can be identified.

Types of Variables

Identify variables for the following three experiments.

You can do it!

Practice

• Does changing the temperature of a ball affect the height the ball will bounce?

Testable Question #1

HotCold

With the person next to you, determine the following:

With the person next to you, determine the following:

What is the dependent variable?

What is the dependent variable?

What is the independent variable?

What is the independent variable?

What are the constants?

What are the constants?

Independent Variable

Dependant Variable

Identify Variables #1

Cold Hot

• Does changing the temperature of a ball affect the height the ball will bounce?

• Constants, or Controlled Variables (which things do not/are not changed) :

* Same ball * Dropped from the same height * Dropped onto the same surface * etc…

Identify Variables #1

• Does changing the color of light affect the growth rate of plants?

Testable Question #2

With the person next to you, determine the following:With the person next to you, determine the following:

What is the dependent variable?What is the dependent variable? What is the independent variable?What is the independent variable? What are the constants?What are the constants?

Independent Variable

(Manipulated)

Dependent Variable (Responding)

Identify Variables #2

• Does changing the color of light affect the growth rate of plants?

• What are the ‘Constants’, the Controlled Variables:

* Same type / size of plant

* Same wattage of bulb

* Same amount of water

* Same soil

* Light on for the same amount of

time

* etc…

Identify Variables #2

• How does the size of a parachute affect the time it takes a toy

hippo to fall 10 feet?

Testable Question #3

With the person next to you, determine the following:With the person next to you, determine the following:

What is the dependent variable?What is the dependent variable? What is the independent variable?What is the independent variable? What are the constants?What are the constants?

Independent Variable

Dependent Variable

Identify Variables #3

• How does the size of a parachute affect the time it takes a toy hippo to fall 10 feet?

• The Constants, or Controlled Variables:

* Same hippo

* Dropped from the same height

* Same parachute fabric

* Same length of strings on the parachute

* etc…

Identify Variables #3