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HOW DO YOU KNOW?HOW DO YOU KNOW?HOW DO YOU KNOW?HOW DO YOU KNOW?HOW DO YOU KNOW?

Experiment!Experiment!Experiment!Experiment!Experiment!

� One way to test a theoryis to set up a controlledexperiment that isolatesvariables and eliminatesoutside factors whichmight influence results.

Have you ever thought youunderstood why somethinghappened the way it did only tofind out that some other factorreally made it happen? Scientistsface this problem every day. Inorder to test an explanation of whysomething happens, they usecontrolled experiments.

A controlled experiment takesinto account all possible factors,or variables, that might cause theeffect being studied. Theexperiment �controls for,� orisolates, several of the variablesand allows scientists to test themone at a time. Using this kind ofsystematic approach, scientists areable to eventually identify thosefactors that play a real causal role.

PROGRPROGRPROGRPROGRPROGRAMAMAMAMAMSYNOPSISSYNOPSISSYNOPSISSYNOPSISSYNOPSIS

SCENE 3 Guess Who? 1:00Stephanie begins testing Z�s ability torecognize a person by his voice alone.She conducts several trials to makesure Z isn�t just a lucky guesser.

SCENE 4 A Thoughtful Parrot 6:00Does a parrot that�s been taught thewords for some objects really knowwhat the words mean? Cast memberDebra investigates. You�ll see how aresearcher set up a series of controlledexperiments to discover whether theparrot was using language.

SCENE 5 The End Results :45The results of Stephanie�s experimentare in. But Z, how did you know who�Me� was?

SCENE 1 �Call Me Back!� 1:30The message on cast member Z�sanswering machine asks him to callback�but who left the message? Zsays it�s his friend Charlie, butStephanie is skeptical that Z knewby the voice alone�she thinks he usedother clues. Z claims he can pick outCharlie�s voice from 100 othervoices, so Stephanie decides to do acontrolled experiment.

SCENE 2 Pucker Up 4:00In the Pyrenees Mountains of France,shepherds communicate bywhistling. Scientists who weren�tconvinced the shepherds actuallytransmitted specific messagesdesigned an experiment to find outwhether the shepherds� whistlingwas really a language.

vocabulary: variable, experiment, control

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BEFORE-VIEWINGBEFORE-VIEWINGBEFORE-VIEWINGBEFORE-VIEWINGBEFORE-VIEWINGDEMONSTRDEMONSTRDEMONSTRDEMONSTRDEMONSTRAAAAATIONTIONTIONTIONTION

AFTER-VIEWINGAFTER-VIEWINGAFTER-VIEWINGAFTER-VIEWINGAFTER-VIEWINGDISDISDISDISDISCUSCUSCUSCUSCUSSIONSIONSIONSIONSION

Ask students how many couldrecognize a classmate just by the soundof her/his voice. Select a volunteer fromthe respondents to sit in front of theclass and be blindfolded. Next, selectfour classmates but don�t reveal theirnames. Explain to students that you�regoing to experiment to see if thevolunteer really can figure out who�stalking, just by hearing her/his voice.Number the participants 1-4 and haveeach person say, �Hi, it�s me.� Ask thelistener to identify each speaker. Once

the experiment is completed, discuss howthe listener had to identify each speaker.(all other clues eliminated, so had todepend on voice) How many speakerswere correctly identified? Is there achance some correct answers were simplyguesses? Do kids think the volunteerproved she/he can identify a classmate byvoice alone?

Remind students that as the volunteer tried to identify someone by voice alone, other clues,like the speaker�s appearance, were eliminated. Explain that this kind of experiment is acontrolled experiment, and that scientists use them all the time. Help kids understand thatthey may have used controlled-experiment techniques without even knowing it. For example,ask how students could find out why a table lamp doesn�t work. (see if it�s plugged in; plugin another lamp to test the electric outlet; etc.) Point out that many factors could cause thelamp to go out. A controlled experiment is designed to identify those factors that play acausal role. Then invite students to watch the video.

Review Stephanie�s controlledexperiment, then compare it with yourBefore-Viewing activity. Whatimportant factors did both you andStephanie eliminate for the controlledexperiment? (ability to see speakers;ability of speakers to say anything theywanted�might give clues to who theywere; etc.) Review details of the shepherd andparrot experiments on the video to makesure students understand the variablesinvolved in each. How did scientistscontrol the experiment with theshepherds? (placed them in separaterooms so the only communication wasthrough whistling; each had to writedown the message) Did the experimentprove the parrot really understood themeanings of the words? (still hard totell, but he seemed to match some wordsto objects)

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LESLESLESLESLESSSSSSON TWOON TWOON TWOON TWOON TWO 3-2-1 CL3-2-1 CL3-2-1 CL3-2-1 CL3-2-1 CLAAAAASSSSSSROOM CONTSROOM CONTSROOM CONTSROOM CONTSROOM CONTACTACTACTACTACT

To use a controlledexperiment todetermine if peoplecan identify commonobjects by touch alone.

MATERIALS:(per class)� 8 mystery cans

(see details below)� chalk� chalkboard eraser� 3 pennies� 4 different buttons� wooden toy block� pencil eraser� marble� 5 pieces uncooked elbow

macaroni

(per student)� pencil

Mystery CansTape the rims of 8 clean, empty 1-lb.coffee cans so there are no sharpedges. Place each can in a largeclean sock so it is completely coveredand the sock sticks up at least 4-6"above the top of the can. Label thecans 1-8.

WHAWHAWHAWHAWHAT TO DOT TO DOT TO DOT TO DOT TO DO:::::1. Prepare the 8 cans before class so that students won�t know what you put into

the cans. Place just one kind of material in each can�the marble in 1 can, all 3pennies in 1 can, all 4 buttons in 1 can, etc. Place the cans around the room ontables and desks, then distribute pencils and copies of the activity sheet, �TouchBase.�

2. Discuss with students the fact that people use a combination of senses�seeing,hearing, touching, smelling, and tasting�to help them recognize things. Referback to Stephanie�s and your class experiments in which only one sense wasused�hearing. Explain that kids will do a controlled experiment to see if theycan identify common objects by touch alone�they may not use their other senses.

3. Explain that each student will move from can to can, stopping just long enoughto feel what�s inside. Kids can�t lift a can, shake it, or look inside, and they can�tdiscuss what�s in a can with classmates. After feeling the object, each studentshould record on Part 1 of the activity sheet what she/he thinks is in the can.

4. Let students begin to move from can to can. When everyone has finished, askwhat kids think is in Can #1. List suggestions on the chalkboard. Follow thesame procedure with the other 7 cans.

5. Reveal the contents of each can. Let kids compile the class results the numberof right guesses and number of wrong guesses�and record that data in Part 2 ofthe activity sheet.

Evaluate the results. How many items were correctly identified? Which itemswere they? Did they have anything in common? Which items were identified bythe fewest number of kids? Why do kids think some items were harder to identifythan others? (some more familiar than others) Let kids come up with differentobjects to put into the cans. Do students think they can predict which will bemore difficult to identify than others? If there were nickels and pennies in thecans, do kids think they would be able to tell the difference between them?

Sometimes, even after collecting data, the results are unclearuntil you graph it. The following chart shows the number ofsunspots that occurred every year from 1930-1960. Have studentsgraph the data and then see if they can find any patterns. Did thegraphing help?

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MATH

1313-2-1 CLASSROOM CONTACT© 1993 Children�s Television Workshop

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