Variables ReviewVariables Review

Dependent VariableDependent Variable

What is being tested or measured.What is being tested or measured.

Independent VariableIndependent Variable

What the Scientist is changing.What the Scientist is changing.

How can I remember? How can I remember?

DEPENDENT VARIABLE DEPENDENT VARIABLE depends on depends on the the INDEPENDENT VARIABLEINDEPENDENT VARIABLE

Example 1 Example 1

The time it takes to run a mile The time it takes to run a mile depends on the amount of daily depends on the amount of daily exercise a person getsexercise a person gets

AnswerAnswer

D.V. – the time it takes to run a mileD.V. – the time it takes to run a mile

I.V. – the amount of exercise the I.V. – the amount of exercise the person is gettingperson is getting

Example 2 Example 2

The higher the temperature of The higher the temperature of water, the faster an egg will cook.water, the faster an egg will cook.

AnswerAnswer

D.V. – the time it takes to boil the D.V. – the time it takes to boil the eggegg

I.V. – the temperature of the waterI.V. – the temperature of the water

Example 3Example 3

An investigation was conducted to An investigation was conducted to see if keeping the lights on for see if keeping the lights on for different amounts of time each day different amounts of time each day affected the number of eggs affected the number of eggs chickens laid.chickens laid.

AnswerAnswer

D.V. – the number of eggs laidD.V. – the number of eggs laid

I.V. – the amount of time the light is I.V. – the amount of time the light is left on left on

Example 4 Example 4

The amount of pollution produced by The amount of pollution produced by cars was measured using gasoline cars was measured using gasoline containing different amounts of containing different amounts of additive. additive.

AnswerAnswer

D.V. – the amount of pollutionD.V. – the amount of pollution

I.V. – the amount of additive in the I.V. – the amount of additive in the gasolinegasoline

Example 5 Example 5

Lemon trees receiving the most Lemon trees receiving the most water produce the largest lemons.water produce the largest lemons.

AnswerAnswer

D.V. – the size of the lemonsD.V. – the size of the lemons

I.V.- the amount of water that the I.V.- the amount of water that the tree receivestree receives

Example 6Example 6

The amount of algae growth in a The amount of algae growth in a lake seems to be directly related to lake seems to be directly related to the number of bags of fertilizer sold the number of bags of fertilizer sold by the local merchants.by the local merchants.

AnswerAnswer

D.V. – The amount of algae in the D.V. – The amount of algae in the lakelake

I.V. – the amount of fertilizer sold by I.V. – the amount of fertilizer sold by the local merchantsthe local merchants

Example 7Example 7

Five groups of rats are fed identical Five groups of rats are fed identical diets except for the amount of diets except for the amount of Vitamin A that they receive. Each Vitamin A that they receive. Each group gets a different amount. After group gets a different amount. After three weeks on the diet, the rats are three weeks on the diet, the rats are weighed to see if the amount of weighed to see if the amount of Vitamin A received affected their Vitamin A received affected their mass.mass.

AnswerAnswer

D.V. – the mass of the ratD.V. – the mass of the rat

I.V. – the amount of vitamin C that I.V. – the amount of vitamin C that that the rat receives each day. that the rat receives each day.

Example 8Example 8

Will the number of nails picked up Will the number of nails picked up by a magnet increase if the magnet by a magnet increase if the magnet is stronger?is stronger?

AnswerAnswer

D.V. – the number of nails that the D.V. – the number of nails that the magnet can pick upmagnet can pick up

I.V. - the strength of the magnetI.V. - the strength of the magnet

Example 9Example 9

Students in science class conducted Students in science class conducted an investigation in which a flashlight an investigation in which a flashlight was pointed at a screen. They was pointed at a screen. They wished to find out if the distance wished to find out if the distance from the light to the screen had any from the light to the screen had any affect on the size of the illuminated affect on the size of the illuminated area. area.

AnswerAnswer

D.V. – the size of the illuminated D.V. – the size of the illuminated area area

I.V. – the distance from the screenI.V. – the distance from the screen

Example 10Example 10

The farther a ball is dropped, the The farther a ball is dropped, the higher it will bounce. higher it will bounce.

AnswerAnswer

D.V. – the height of the bounceD.V. – the height of the bounce

I.V. – the height of the dropI.V. – the height of the drop