IDENTIFYING AND CONTROLLING VARIABLES

LECTURE NOTES BY MR. SYLVESTER SAIMON SIMIN

MPKS

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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INTRODUCTION

• In scientific inquiries, we investigate to find out what causes something to happen – to find the effect of one variable on another.

• We investigate the effect of changing only one of the variables; we must keep the other variables constant. In this way, we can tell whether that single variable has an effect.

• The idea behind identifying and controlling variables is that we must be sure that what we think caused an effect did in fact cause it.

• This skill requires children to have the ability to perceive that there is more than one attribute (physical & behaviour, interactions) to given objects (concrete operational stage)

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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DEFINITION

• VARIABLES:– FACTORS / CONDITIONS THAT CAN CHANGE OR

BE CHANGED IN AN EVENT OR SYSTEM– THINGS WITHIN AN INVESTIGATION WHICH CAN

BE CHANGED OR KEPT THE SAME

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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TYPES OF VARIABLES

• MANIPULATED VARIABLE (INDEPENDENT VARIABLE / INPUT VARIABLES) – WHAT TO CHANGE– FACTOR OR CONDITION THAT IS INTENTIONALLY

CHANGED IN AN EXPERIMENT / INVESTIGATION.

• RESPONDING VARIABLE (DEPENDENT VARIABLE / OUTCOME VARIABLE) – WHAT TO MEASURE– FACTOR OR CONDITION THAT WILL BE

AFFECTED AS A RESULT OF THAT CHANGE (MV)

• CONTROLLED VARIABLE (CONSTANT VARIABLES) – WHAT TO KEEP THE SAME– FACTOR OR CONDITION THAT IS DELIBERATELY

NOT CHANGED (KEPT THE SAME)

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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TYPES OF VARIABLES

MANIPULATED VARIABLE (WHAT TO CHANGE)

RESPONDING VARIABLE (WHAT TO MEASURE)

CONTROLLED VARIABLE (WHAT TO KEEP THE

SAME)

FACTOR OR CONDITION THAT IS INTENTIONALLY

CHANGED IN AN EXPERIMENT /

INVESTIGATION TO FIND OUT WHAT EFFECT IT HAS

FACTOR OR CONDITION THAT IS AFFECTED AS A RESULT OF CHANGING

THE MANIPULATED VARIABLE

FACTOR OR CONDITION THAT IS DELIBERATELY

NOT CHANGED (KEPT THE SAME) TO MAKE IT A FAIR

TEST

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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COMPLEXITY OF VARIABLE

• EACH TYPE OF VARIABLE NEEDS TO BE OBSERVED AND MEASURED.

• THE DEGREE OF COMPLEXITY OF THOSE MEASUREMENTS WILL VARY ACCORDING TO THE AGE AND EXPERIENCE OF STUDENTS AND DEMANDS OF THE INVESTIGATION.

• 4 CLASSES OF COMPLEXITY OF VARIABLES:– CATEGORIC : DESCRIPTIVE EG. COLOUR– DISCRETE : MEASURED IN WHOLE NUMBERS EG. NUMBER

OF LEGS OF INSECTS– CONTINUOUS : MEASURED IN RANGE OF NUMBERS

INCLUDING FRACTIONS/DECIMALS EG. TEMPERATURE– DERIVED : CALCULATED FROM MEASUREMENTS OF

OTHER VARIABLES EG. SPEED

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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COMPLEXITY OF VARIABLES

CATEGORIC VARIABLE

DISCRETE VARIABLECONTINUOUS

VARIABLEDERIVED VARIABLE

• SIMPLE DESCRIPTIVE VARIABLE – COLOUR

• NO NUMERICAL VALUE

• EG: HOT, WARM, COLD, TYPE OF BIRD

• WHOLE NUMBER VALUE – 4 BOUNCES

• EG: NO. OF LEGS, POPULATION, NO. OF TABLETS

• DISCONTINUOUS VARIABLE

• NUMERICAL VALUE ANYWHERE ALONG A CONTINUUM OF NUMBERS INC. DECIMALS

• EG: TEMPERATURE, VOLUME, MASS, TIME

•CALCULATED FROM OTHER VARIABLES WHICH MUST FIRST BE MEASURED•POTENTIAL ENERGY = MASS X HEIGHT X g•EG: VELOCITY, ACCELERATION, DENSITY

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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KEY VARIABLESINVESTIGATION MANIPULATED RESPONDING CONTROLLED

COLOUR OF BALLS (CATEGORIC)

HEIGHT OF BOUNCE (CONTINUOUS)

• HEIGHT OF DROP• SIZE OF BALL• SURFACE BOUNCED ON• TYPE OF BALL

COLOUR OF BALLS (CATEGORIC)

NUMBER OF TIMES IT BOUNCES AFTER A DROP (DISCRETE)

• HEIGHT OF DROP• SIZE OF BALL• SURFACE BOUNCED ON• TYPE OF BALL

HEIGHT FROM WHICH THE BALL IS DROPPED (CONTINUOUS)

HEIGHT OF THE FIRST BOUNCE (CONTINUOUS)

• COLOUR OF BALL• SIZE OF BALL• SURFACE BOUNCED ON• TYPE OF BALL

HEIGHT OF THE DROP INCORPORATED INTO m x g x h CALCULATION (CONTINUOUS / DERIVED)

HEIGHT OF THE FIRST BOUNCE (CONTINUOUS)

• COLOUR OF BALL• SIZE OF BALL• SURFACE BOUNCED ON• TYPE OF BALL

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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SUGGESTED APPROPRIATENESS OF VARIABLES

LEVEL (YEAR/FORM)

MANIPULATED VARIABLE

RESPONDING VARIABLE

PRE-SC

Y1

Y2

Y3

Y4

Y5

Y6

F1

F2

F3

F4

F5

NOT REQUIRED

1

1

1 CONTINUOUS

2 OR MORE VARIABLES

1, PROBABLY CONTINUOUS OR

DERIVED

NOT REQUIRED

1

1

1 CONTINUOUS

1, PROBABLY CONTINUOUS OR

DERIVED

INCREASING COMPLEXITY

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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IDENTIFYING VARIABLES:WHAT ARE THE VARIABLES IN THESE STATEMENTS?

“The time it takes to run a kilometer depend on the amount of exercise a person get”

VARIABLE : _______________________

VARIABLE : _______________________

Time to run a kilometer

amount of exercise

NOTE:

It would not be correct to name just time or exercise. We must include how each variable will be measured or described.

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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IDENTIFYING VARIABLES:WHAT ARE THE VARIABLES IN THESE STATEMENTS?

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

VARIABLE : _______________________

VARIABLE : _______________________

Temperature of water

time needed for an egg to cook

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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IDENTIFYING VARIABLES:WHAT ARE THE VARIABLES IN THESE STATEMENTS?

“An investigation was done to see if keeping the light on for different amount of time each day affected the number of eggs chickens laid”

VARIABLE : _______________________

VARIABLE : _______________________

Hours (or amount) of light

number of eggs

NOTE:Just light and eggs however, would be incorrect

descriptions of the variables. IT MUST BE MEASURABLE.

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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CLASSIFYING VARIABLES : MV, RV, CV

“The amount of pollution produced by cars was measured for cars using gasoline containing different amount of lead”

MANIPULATED VARIABLE : _______________________amount of lead in gasoline

RESPONDING VARIABLE : _______________________amount of pollution

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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CLASSIFYING VARIABLES : MV, RV, CV

“more bushels of potatoes will produced if the soil is fertilized more”

MANIPULATED VARIABLE : _______________________

RESPONDING VARIABLE : _______________________

amount of fertilizer

number of bushels of potatoes

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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CLASSIFYING VARIABLES : MV, RV, CV

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

MANIPULATED VARIABLE : _______________________

RESPONDING VARIABLE : _______________________

Amount of Vitamin A

Weight of rats

NOTE:

Weight of rats may not be affected if Vitamin A is not essential but the weight of rats is still the RV.

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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CLASSIFYING VARIABLES : MV, RV, CV

“A student wanted to test how the mass of a paper airplane affected the distance it would fly. Paper clips were added before each test flight. As each paper clip was added, the plane was tested to determine how far it would fly”

MANIPULATED VARIABLE : _______________________

RESPONDING VARIABLE : _______________________

Number of paper clip added

Distance flown

CONTROLLED VARIABLES : _______________________The same plane was used for each trial

Apr 8, 2023 SYLVESTER SAIMON SIMIN, JSM, MPKS

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THANK YOU FOR YOUR ATTENTION AND COOPERATION