Guided Inquiry Laboratory J. B. Allen, L. N. Barker, aml J. H. Ramsden U. S. Military Academy, West Point, NY 10996
Because of its focus on the scientific method of investigation, general chemistry offers very fertile ground for improving the critical thinking skills of students. In this vein, the Chemistry Department at the U. S. Military Academy (USMA) is emuhaiizine the inteeration of oroblern-solvine techniques in ;he clas&oom and-the development of mo; challenging laboratory exercises in its general chemistry courses. The primary purpose of this article is to illustrate the concepts involved in converting a traditional "verification" experiment (where the student verifies a principle taught in the classroom) to a "guided inquiry" experiment (where the student discovers the concept for himself or herself using his or her own laboratory data). While this isnot a novelidea, we feel the time is right to reemphasize discovery type experiments. We have converted several of our general chemistry experiments t o the discovery format and have surveyed officer instructors and students on their reactions. The verification format had traditionally been used a t USMA: however, our instructors and others (1-13) complained that the students were treating the experiments as "co~~khook"exercises, that thestudents were not stimulated intellectually because they only had to recall their classroom work to do well, and that there was little motivation for the students to prepare adequately for each experiment. Another major problem we had encountered is best stated in the words of Pickering (5) who said, ". . . the student is expected to produce a verification of something that he already knows, and so ends u p trained to ask what a result is supposed to he, not what it in fact is!' Based on a studv of our eeneral chemist^ lahoratorv orogram (14), we decided to convert several exiting verifiiaiion experiments to the guided inquiry format. The experiments converted-gas laws, freezing point depression, and chemical kinetics-were selected because: (1) the experiments required the collection and graphing of data from which an empirical mathematical relationship could be developed, (2) the mathematical relationship developed could be applied to other laboratory investigations, (3) the experiments allowed the cadets to acquire a better feeling for how chemical knowledge is obtained, and (4) the cost of conversion in terms of chemicals and e a u i ~ m e n was t minimal. While a t least one laboratory man& (i5) contains experiments in the guided inquiry format, readers may also wish to write their own experiments and then test them to determine if they meet the objectives of their laboratory programs. While there is no set procedure for converting averification experiment to a guided inquiry format, the steps and suggestions in Table 1should prove useful. The structuring of the experiment is in itself an excellent problem-solving exercise that would stimulate the critical thinking skills of teaching assistants. Our guided inquiry experiments were structured so that the students could comolete the work in the same amount of time required for the verification experiments. We will use the freezine ooint de~ressionexoeriment to illustrate a conversion briefly. able 2 provides a comparison of the two formats. Notice ~articularlvthe difference in the objectives for the two approaches. ~ h original k verifica-
tion freezing point depression experiment made use of the relationship, A T f = iKtm,and required the students to calculate the molec&r weight of anmknown solute. The stu-
Table 1. How to Convert a Verlllcatlon Experiment to a Gulded Inmlrw Format 1. Select an Experiment a) where relatively simple and straightforwardconcepts are utlllred, b) where data is wllected using an unwmplicated apparahs. C) where the collecteddata lends itself to "discovery"-type analysis; e.g.. it allows lha determination of an empirical mathematical relationship. and d) where the conclusions hom lha analysis can be tested. 2. Modify the verification experiment introductory material so h t the princlpal wncepls are not "taught" before the laboratory. 3. Reduce lha detailed proceduralsteps significantly so thet the student must "think" about haw to collect lhe necessary data and how to analyze It. 4. Include a step or procedure toward the end of the experiment which allows the student to verify hls analysis and conclusions about lha principal concept(s1. 5. Include shat discussion "hugM" questions in lha laboratory report.
Table 2.
A Comparlron of
Purposa Scheduling
Objectives
Freezing Point Depression Verlllcatlon and Guided inquiry Experiments Verification
Guided Inquiry
Verily Concepts Lab sheduled aner materlal presented in classrmm (I) Determine moiecular weight of unknown solute. (2) Determine percent dissociation of benzoic acid.
Discover Concepts Lab scheduled before material presented in c1assroom. (1) Develop empirical mathematical relationship beween AT, and molality. (2) Determine moleoular welght of unknown solute using empirical mlation~hlp. (3) Determine he components of the w n stant, c, in he e m plrical reMionship. No theoretical background presanted. lh hoduction llmlted to Infamation necessary to process wllected e~perimenlaldata. Less detailed step-by-step procedure. Must be very knowledgeable of the entire experimam and be prepared lo guide students when necessary.
Lab lntrcductim
Relevant equations and concepts to be verified are disc~ssed.
Lab Pmcedure
Detailed stepbyatep procedure. Primary duty is to supervise administratively the laboratory with minimal direct involve m n t w'* he *.
lnsbuctn or Teaching Assistant Involvement
Volume 63 Number 6 June 1986
533
dents were then required to calculate the van't Hoff factor (i) and the percent dissociation for henzoic acid. In the guided inquiry version, data for determining the empirical mathematical relationship were ohtained by measuring the freezing points of solutions containing the-solute cyclohexane in tert-hutyl alcohol. (Each two-person lahoratory group was responsible for only one specific volume of cyclohexane.) The data were then shared among the laboratory groups and a graph of ATrversus molality constructed. (A possible variation in this step would be to require the students to determine what to plot and to "find" the A T dependence from a Tversus m plot.) Students were asked to determine from their graph a mathematical relationship which related ATi and m. I t was hoped that they concluded that ATr = cm and then calculated c from the s l o ~ eof a graphical plot or a ralrulator linear regression program. Hecause a major advantage of guided inquiry experiments is the requirement for studrntr toapply acquired knowledge tn a new situation, the students w t w next required to use their derived mathematical relationshin to calculare the molecular weight of an unknown solute. 6hloroacetic acid was used because a laree solute nercent dissociation was necessary to lead into a &hubsequent discussion of the components of the constant, c. Students were briefed on safetv considerations (especially critical in guided inquiry experiments) prior to beginning work and instructors closelv monitored student woik. As is often the case in guided inquiry exoeriments, some instructor h ~ n t to s the students maybe;eq&d. Since most general chemistry lahoratory programs are run hv teaching assistants. tr should he elnohasized t h ~ their t nrelahoratorv preparation and anticipation of questions is critical to th; success of any discovery type experiment. We believe, however, that gifted teachers are not a prerequisite for success. Instructor participation during this experiment was primarily limited to asking leading questions of the students. The students were then reauired to calculate the value of the constant, c, using the actual molecular weight of chloroacetic acid. This led nicely into an analvsis of the components of the constant, c. he; were told that the constant, c, was actually composed of two factors, one dependent on the particular solvent { K ~and J one dependent bn the degree of dissoriation of the solute (I). Using the two values of c, they were reqttired to discuss the relative degree of dissoriatiun of cyclohexaoe and thr unknown solute. The final auestionscarried theroncent ofcollieative .roo. erties furthe;.
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1) "If t w u different solutes dissociate to the same extent in a particularuulvent,does rt necessnrils followthat their values ofi will be rqual'" (Hint: NaCl w r s w NmSOA. Z)."~etermine the actual free;& ooint of tert-hutvl alcohol from the 'Handbook of Chemistry a;d-~hysics'. Is the &oh01 you used in this experiment 'pure'? Justify your answer." (A practical problem.)
By the end of the experiment the student had acquired a basic insight into colligative properties. While some step-bystep experimental procedures were used, no detailed theoretical background-was presented in theclassroom prior to the experiment, so that the experiment was essentially a "discovery" type experience for the student. As a result of the generally favorable response by the students and the enthusiasm of the instructors for the new guided inquiry format, "open inquiry" (16) experiments
534
Journal of Chemlcal Education
Table 3. Summary of Student QuerllonnalreResponses Perwnt 01 RBSPO~SBS Strongly Strongly Agree Disagree ReS~Onse
1
7
3
.
4
1) My powers of observation were stimulated
anddeveloped more by the guided inquiry experimentsthan by the verification experiments.' 2) Guided inquiry experimentsenhancedmy understanding of chemical conwpts to a greater degree than verification experimants.' 3) 1 think this course would be better it more experimentswere guided inquiry experiments.' 'First mw ot m a
ham ~manced~ e n a aCnanstr, l 1984-1985 1200 writs). 1983 I884 (200 s1UdBnts). sndmlra row hom Gsnaal U a m r"/ 1984-19851900 nldanul IS
88Com row ham AOvanced General Uamlmy
were evaluated in our Advanced General Chemistry course and some guided inquiry experiments were tested in our basic General Chemistry course. Specific questions on the lahoratory report were c h a n ~ e dor reworded this vear to maintain novelty and to mincmize any advantage freshmen might have obtained by talking to sophomores about the experiments. Our General ~ h e m i s t r vstudents did not have -~ - ~ - ~ time, in a 2-h lab period, to analyzethe components of the constant c durine the freezine -.noint deoression ex~eriment. It is recommen(ied, however, that analysi* of this constant hedone if time oerrnits (3-h lab oeriod) or if thestudentsare of an advancedcaliber. Student opinions of the a i d e d inauirv laboratorv format are summarized in able-3. From the-written c&ments received, the students acknowledged that the guided inquiry experiments were more difficult and at times more frustrating than the standard verification experiments. However, they ranked guided inquiry experiments high in terms of interest, development of analytical thinking ability, and problem solving. We believe that guided inquiry experiments are an important tool not only to improve student critical thinking skills and prohlem-solving abilities hut also to help reduce the drudgery and "cookbook" style of verification laboratory exoeriments. Interested readers are encouraeed to write to thk authors to obtain copies of old verification experiments and "new" a i d e d inauirv in order t o observe . . ex~eriments . first hand tKe conversion process. ~
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Literature Cited (1) Hanaon. A. L. J. Chsm.Edu. t982.59.671. (2) Venkalachelam. C.;Rudo1ph.R W. J.Chem. Edue. 1914.51,479. 13) Pave1ich.M.J. J.Chem.Edue., 1982,59,721. ( 4 ) Fsbr, G. C.: Martin, E. M . J. Coll. Sci. Teach. 1983.12.222. (5) Pickering, M. Chron. High. Edue. 1980.19,80. (61 Wartell. M.A. J. Chem. Edue. 1913.50.361. (7)Pavelieh, M. J.; Abrahams. M.R.J. Coll. Sci. Teach. 1971,7,23. (81 Ophardt, C . E. J. Cham.Edur. 1918,55.485. (91 Me1lon.E.K. J. Chem.Edue. 1918,55,517.
110) Paveiieh, M. J.;Ahraham,M. R. J. Chem.Educ. 1919,56,1W. 111) Ryan,M. A.;Robinson,D.;Cmichacl,Jr., J. W . J . Chem.Edue. 1980,57,E42. 112) Goodman, W.D.:Bean,J.C. J.Chem.Educ. 1983.60.483. 113) Wdbberg, G. J. Cham. Ed-. 1983.60.125. (14) A1len.J.9;Barker. L. N.;Zart.K. W. "AStudyoitheGeneralChemiatlyLaboratory Program at U S M A 1983. 115) Abraham, M. R.;Pavelich, M. J. " h q u i r i ~into Chcmi8W; Waveland: P r a p e t Heights, IL, 1979. 116) Abraham, M. R. J. &a. Sei. Toarh. 1982,19,155.
