P LEASE D O N OW Study for your NEWTON’S LAWS quiz at Level 0.

I DENTIFYING V ARIABLES & D ESIGNING I NVESTIGATIONS U NIT 2 D AY 5 O CT. 10/11, 2012

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?

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 we think may cause something to happen

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

CONSTANTS: A constant is something that a scientist keeps the same in an experiment. Most experiments have more than one constant.

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 took to put the puzzle together The time was observed and measured by the scientist

W HAT WAS A CONSTANT ? 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.

C ONTROL G ROUP VS. E XPERIMENTAL G ROUP CONTROL GROUP: Something that is used for comparison because it is normal. Nothing new happens to this group! EXPERIMENTAL GROUP: Something that is unknown and compared against the control group. Something NEW happens to this group!

Something that is used for __________ because it is ________. Something that is UNKNOWN and is __________________________. COMPARISON NORMAL COMPARED AGAINST THE CONTROL GROUP EXAMPLE # 0: A new drug, called Slurp, claims it fights zits very well. You want to find out if it is true. You decide to give 10 friends Slurp and have 10 other friends just keep doing whatever they normally do to keep away zits. After a week, you have them report back to you. The control group is : _______________________________. The experimental group is _______________________________. 10 friends who do what they normally do to keep away zits. 10 friends who use Slurp

E XAMPLE #1: Ms. Alanis wants to know how sunlight affects the height of the 2 identical plants in her office. So, she puts plant A in the sunlight for 3 hours and puts plant B in the sunlight for 8 hours. She gives each plant ½ cup of water each day and measures the height of each plant at 5 pm every day. Constants? ____________________________ _____________________________________ Types of plants, time she measures height, type of soil plants are potted in, amount of water she gives them, their location.

E XAMPLE #2: Ms. Lulla likes to have hot coffee in the morning. However, sometimes she is so busy welcoming all of the GCP scholars that she leaves her coffee on her desk and doesn’t get a chance to drink it for an hour. Ms. Lulla’s favorite mug only keeps her coffee warm for 30 minutes, so Ms. Lulla tries to find a coffee mug that will keep her coffee warm the longest. She buys 2 mugs: a thick-walled mug and a thin-walled mug. Ms. Lulla makes a container of coffee and pours equal amounts into all three mugs. She takes the temperature of both mugs every 5 minutes for an hour & records the temperature. Control Group:_____________________________ Experimental Groups:_______________________ Constants: ____________________________ Favorite mug Thick-walled mug AND thin-walled mug Type of coffee, amount of coffee, starting temperature of coffee, time she records temperature, location of mugs

E XAMPLE #3: The new ad campaign for Wheaties says that eating Wheaties for breakfast causes people to smile more in a given day. Because Ms. O’Neil is a scientist, she is skeptical of this claim by Wheaties. Therefore, she gathers a group of 15-year-old students, 10 male and 10 female, and performs “background” interviews with people close to them to see how much they smile on a given day. She then takes half of the males and half of the females and has them eat a bowl of Wheaties every morning for a month. The other half of the students eat their regular breakfasts. At the end of the month, she re-interviews the people close to the students in order to see if their smiling “habits” have changed or not. Control Group:_____________________________ Experimental Group:_______________________ Constants: ________________________________ Students who eat regular breakfasts Students who eat Wheaties Age of students, time they eat breakfast, eat breakfast daily

E XAMPLE #4: Mold has been shown to grow on bread that is left at room temperature (70 degrees). So, Mr. Jaml leaves a loaf of WonderBread on his countertop at different temperatures until he sees mold growing. The bread is kept at 40 degrees, 70 degrees, & 86 degrees. Control Group:_____________________________ Experimental Groups:_________________ Constants: ______________________________ 70 degrees 40 and 86 degrees Type of bread, location of bread

E XAMPLE #5: Students are always tired in Ms. O’Neil’s 1 st period class, so she decides to give them coffee instead of the usual orange juice with their breakfast in the hope that caffeine will wake them up. Half of her 1 st period class drinks coffee with their breakfast and the other half drinks the same amount of orange juice. During 1 st period, she counts how many students fall asleep. Control Group:_____________________________ Experimental Group:_______________________ Constants: ___________________________ Students who drink orange juice Students who drink coffee Time she counts the # asleep, amount of liquid they drink.