CAUSE AND EFFECT
Relationship between two things when one thing makes something else happen
Scientists use an experiment to search for cause and effect relationships
Experiments are made so that changes to one item cause something else to vary or change in a predictable way
EXAMPLE Does eating a McDonald’s Big Mac everyday
cause people to be obese? What is the cause and effect relationship?Which variable may
CAUSE something else to happen?
Which is changing due to the other one?
TESTABLE QUESTIONS
Turn cause and effect into something that can be tested They make a testable question
Testable Questions:1. Not based on opinion2. Must have clear cause and effect
relationship3. Must be measurable
DOES EATING A MCDONALD’S BIG MAC EVERYDAY CAUSE PEOPLE TO BE OBESE?
Let’s make it testable:
Does it have clear cause and effect? _________
Is it based on opinion? _________
Is it measurable? _______ How can we make it measureable?
______________________________________
NOT TESTABLE
YesNo
No
Explain what we will measure
YOUR TURN
Write TQ next to each question that can be tested.
For the TQ’s circle the factor CAUSING something to change
And underline the EFFECT
For those that are not TQ’s, write why they are not testable
TQ OR NOT
1. Which type of music is better Hip Hop or Punk?
2. Does reading 30 minutes each night help your grades?
3. Will eating protein shakes increase my upper body strength?
4. Which brand of shoe is better for running, Nike or Adidas?
5. Does fertilizer help a plant grow taller?
EXPERIMENTAL VARIABLES
Independent Variable – something that is changed by the scientistWhat is being testedWhat is manipulated/changed
What is the effect of eating a McDonald’s Big Mac every day on a person’s weight?
Independent Variable???
IV = Amount of Big Macs that someone eats
EXPERIMENTAL VARIABLES
Dependent Variable – something that might be affected by the change in the independent variableWhat is observedWhat is measuredThe data collected during the investigation
What is the effect of eating a McDonald’s Big Mac every day on a person’s weight?
Dependent Variable???
DV = Person’s Weight in (kg)
EXPERIMENTAL VARIABLES
Controlled Variable – a variable that is not changed, kept the same or constant Also called constantsAllow for a “fair test”
STUDENTS OF DIFFERENT AGES WERE GIVEN THE SAME JIGSAW PUZZLE TO PUT TOGETHER. THEY WERE TIMED TO SEE HOW LONG IT TOOK TO FINISH THE PUZZLE.
WHAT WAS THE DEPENDENT VARIABLE?
The time it to put the puzzle togetherThe time was observed and measured by the scientist
WHAT WAS A CONTROLLED VARIABLE?
Same puzzleAll of the participants were tested with the same puzzle.
It would not have been a fair test if some had an easy 30 piece puzzle and some had a harder 500 piece puzzle.
THE GREATER THE AMOUNT OF SOAP IN A SOAP AND WATER MIXTURE, THE BIGGER A SOAP BUBBLE CAN BE BLOWN.
Design an investigation to test this hypothesis.
Identify the variablesWhat exactly will be changed?
How will it be changed?What exactly will be measured?
How will it be measured?
THE FARTHER A BALL DROPS, THE HIGHER IT WILL BOUNCE.
Design an investigation to test this hypothesis.Identify the variablesWhat exactly will be changed? How will it be changed?
What exactly will be measured? How will it be measured?
http://www.youtube.com/watch?v=tG5NX7fC8VM&p=F515918DB6082821&playnext=1&index=15
What color do Sharks prefer?