DO NOW – L EVEL 0 Pass in Cornell Notes Homework Read “Risk Taking” Article

I DENTIFYING V ARIABLES & D ESIGNING I NVESTIGATIONS

C AUSE AND E FFECT 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

E XAMPLE 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?

T ESTABLE QUESTIONS Turn cause and effect into something that can be tested  They make a testable question Testable Questions: 1. Not based on opinion 2. Must have clear cause and effect relationship 3. Must be measurable

D OES EATING A M C D ONALD ’ S B IG M AC 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? ______________________________________

T ESTABLE QUESTION What is the effect of eating a McDonald’s Big Mac every day on a person’s weight?

Y OUR 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?

E XPERIMENTAL V ARIABLES Independent Variable – something that is changed by the scientist What is being tested What 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

E XPERIMENTAL V ARIABLES Dependent Variable – something that might be affected by the change in the independent variable What is observed What is measured The 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)

E XPERIMENTAL V ARIABLES Controlled Variable – a variable that is not changed, kept the same or constant Also called constants Allow for a “fair test”

F OR E XAMPLE :

S TUDENTS OF DIFFERENT AGES WERE GIVEN THE SAME JIGSAW PUZZLE TO PUT TOGETHER. T HEY WERE TIMED TO SEE HOW LONG IT TOOK TO FINISH THE PUZZLE.

I DENTIFY THE VARIABLES IN THIS INVESTIGATION.

W HAT WAS THE INDEPENDENT VARIABLE ? Ages of the students Different ages were tested by the scientist

W HAT WAS THE DEPENDENT VARIABLE ? The time it to put the puzzle together The time was observed and measured by the scientist

W HAT WAS A CONTROLLED VARIABLE ? Same puzzle All 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.

A NOTHER EXAMPLE :

T HE HIGHER THE TEMPERATURE OF WATER, THE FASTER AN EGG WILL BOIL.

Independent variable – temperature of water Dependent variable – time to cook an egg

L AST ONE :

T HE TEMPERATURE OF WATER WAS MEASURED AT DIFFERENT DEPTHS OF A POND.

Independent variable – depth of the water Dependent variable – temperature

D ESIGNING I NVESTIGATIONS

T HE 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 variables What exactly will be changed? How will it be changed? What exactly will be measured? How will it be measured?

T HE FARTHER A BALL DROPS, THE HIGHER IT WILL BOUNCE. Design an investigation to test this hypothesis. Identify the variables What exactly will be changed? How will it be changed? What exactly will be measured? How will it be measured?

&playnext=1&index=15 What color do Sharks prefer?

W HILE WATCHING VIDEO : What is the IV Remember: this is the variable that is being changed What is the DV This is the variable that is being measured What is the testable question?