Lab 1 The Scientific Method

Transcription

1 INTRODUCTION The fllwing labratry exercise is designed t give yu, the student, an pprtunity t explre unknwn systems, r universes, and hypthesize pssible rules which may gvern the behavir within them. Scientific Methd There are many different scientific methds. They are all similar in their shared use f careful, deductive reasning. We will use the fllwing versin f the Scientific Methd: Hypthesis Observatin recgnize a phenmenn Hypthesis prpse an explanatin and predict its cnsequences Experiment devise a test t determine the validity f yur hypthesis Analysis cmpare results with hypthesis, re- test t check fr errr Cnclusin what yu learn frm experiment and hypthesis The essence f the scientific methd lies in the hypthesis. Hypthesis can be defined as an educated guess; a reasnable explanatin f an bservatin r experimental result tested by experiment. A gd hypthesis must meet three criteria. First, it must be simple and apply t the phenmena in questin. This is knwn as Validity. Secnd, it must be testable, that is, repeated experimentatin must be able t cnfirm r disprve it. The ability t be disprven is a subtle, yet imprtant pint. Fr a hypthesis t be scientific it must be falsifiable. Third, a gd hypthesis must be able t predict the utcme f future experiments r predict the existence f as- yet- unbserved phenmena. PROCEDURE Part A: The Hypthesis Machine The hypthesis machine is a device that cnsists f a series f channels within a plastic casing. In the center f the casing, there is a cvered sectin with a space t insert varius shaped blcks. The varius shaped blcks are hidden frm view, and depending n the shape and psitin f the blck, balls that rll dwn the channels can be stpped r have the path f their mtin changed by the blck. The bject f the experiment is t make a hypthesis abut the shape and psitin f the blck in the hidden area based n the behavir f steel balls that are drpped thrugh. 1

2 Discuss with yur grup members what makes a gd hypthesis. What wuld be a gd hypthesis fr this demnstratin? What factrs culd cause a change in the path f the mtin f the ball? Are these likely pssibilities? Why? Why nt? Yur labratry instructr will set up the machine and drp the balls, ne at a time. Yur instructr will d this fr three different shaped blcks. As the instructr drps the balls, the class will discuss pssible shapes. As the class des this part f the exercise, take careful ntes and answer the questins n the wrksheet at the end f this dcument. Here are sme questins yu might want t cnsider t help in yur decisin making prcess. 1. What happens t each ball as it ges thrugh the machine? 2. What factrs d yu cnsider while hypthesizing abut the shape? 3. What cnclusins d yu draw abut each shape? What features f the paths wuld yu use as basis fr yur cnclusins? 4. Were yur cnclusins abut each shape crrect? If nt, why? CHECKPOINT 1: HAVE YOUR TA CHECK YOUR WORK BEFORE PROCEEDING Part B: The Checkerbard Investigatin Each universe cnsists f the same basic system, which is a checkerbard, sme red and black checkers, and a set f allwed cnfiguratins (a set f pssible checker placements). Wrk in grups f apprximately fur students try t discver the rules which determine these cnfiguratins; that is, under what circumstances and in which squares can the checkers be placed accrding t the rules f the universe. Fr each checkerbard universe yu explre, chse ne persn frm yur grup t represent the universe. This representative will be given the rules f the universe, and will be in charge f the checkers. This student s jb will be t tell the thers whether a particular checker is allwed, by the rules f the universe, in a particular space. The ther three members f the grup will take turns placing checkers. Each time a checker is placed n the bard, the representative will declare it as either allwed, r nt allwed, accrding t the rules f the universe. If a checker placement is allwed, it is left n the bard. If it is nt allwed, the checker is remved frm the bard. Frm the results f these placements, yur team will have t hypthesize rules fr the universe. When yur team feels that it has cme up with a rule that crrectly predicts the allwed and disallwed placements, submit it in writing t the representative. Fr a hypthesis t be valid, it shuld be written dwn n paper. 2

3 If it is crrect, yu may g n t the next universe. If the hypthesis is crrect but incmplete, r if it is incrrect, the representative shuld say s and yu must cntinue t explre until the entire rule is determined. Yu will nt be penalized fr making incrrect hyptheses. As yu explre each universe, take careful ntes and answer the questins n the wrksheet at the end f this dcument. Yur ntes shuld include: the universe s number descriptin f the placements yu tried in the rder they were tried yur strategy behind each placement r sample set f placements t test a pssible rule in the universe each hypthesis made (crrect, incrrect, r partially crrect) The final crrect hypthesis Explre a ttal f ten universes. Chse a new representative each time yu g t a new universe. When yu are the universe representative, be very careful in judging whether a mve is allwed r nt. If yu make a mistake, it culd make things very cnfusing fr the team, and yu may have t start all ver with that universe. If yu are unsure f a placement, r an entire rule, cnsult with yur labratry instructr befre answering. If yu have t start ver because the representative made a mistake, d nt cunt that universe. If yu start t run ut f rm n yur checkerbard befre determining the crrect rule, yu can start the universe ver. If yu have time after cmpleting the ten assigned universes, have each member f the grup take a turn as the representative and make up rules fr a new universe. Make the rules as riginal and as crazy as pssible. Observe hw lng it takes fr ther members f the grup t deduce the rules. CHECKPOINT 2: HAVE YOUR TA CHECK YOUR WORK BEFORE PROCEEDING 3

4 SCIENTIFIC METHOD - WORKSHEET Part A: The Hypthesis Machine Answer the fllwing questins fr three f the blcks yu investigated. Blck 1: 1. What happens t each ball as it ges thrugh the machine? 2. What factr(s) did yu cnsider while hypthesizing abut the shape f the blck? 3. What features f the path f each ball helped yu in yur decisin making prcess? 4. What cnclusin did yu draw abut the shape f blck 1? Blck 2: 1. What happens t each ball as it ges thrugh the machine? 2. What factr(s) did yu cnsider while hypthesizing abut the shape f the blck? 3. What features f the path f each ball helped yu in yur decisin making prcess? 4. What cnclusin did yu draw abut the shape f blck 1? 4

5 Blck 3: 1. What happens t each ball as it ges thrugh the machine? 2. What factr(s) did yu cnsider while hypthesizing abut the shape f the blck? 3. What features f the path f each ball helped yu in yur decisin making prcess? 4. What cnclusin did yu draw abut the shape f blck 1? CHECKPOINT 1 Part B: The Checkerbard Investigatin Reprt yur bservatins fr three ut f the ten Universes yu investigated in the space prvided belw. Fr each reprt make sure yu address the fllwing pints. (a) the universe's number (b) descriptin f the placements yu tried in the rder they were tried (c) the strategies yu adpted fr the placement f the checkers (d) the crrect (r incrrect) hypthesis yu made (e) the "final" crrect hypthesis. 5

6 Universe 1: Universe 2: Universe 3: CHECKPOINT 2 6