Patrick E. Hoggard Polytechnic Institute of New York Brooklyn, NY 11201
A Guided Design Approach to Teaching General Chemistry
Guided Design, as originated hy Charles Wales and Robert Stager a t the West Virginia University (1-4), is a method of instruction organized around a series of structured projects, which students work through in small groups during class hours. The traditional lecture and the linear development of subject matter are partly or totally discarded. Guided Design emphasizes decision-making, both as a skill to be learned and nrocedure in the oreanization of as a unifvine- svstematic " project materials. The projkct must require tharthe students master certain skills and conceDts in order to render a defensible decision. The ~ t meted out to the students in a sequence of . r o.i e c is printed Instruction and Feedhnrk sheets, which are in turn hased on stnndard steps in the decision-makinp process. The group receives one 1n&uction a t a time, discu& that step, and agrees on a response. The response is monitored by the instructor, and, if it is acceptable, the group receives a Feedback and a new Instruction. The Feedback represents a response an experienced person might have made but, in general, not the only good response. The instructor a d s as a consultant, providing facts, guidelines, and explanations as needed. As an example, we may examine the steps in a particular project, "Oklahoma Story," in which the group in the narrative discovers that farmers in a certain area have been using the same fertilizer (6-10-6) for some time and attempt to figure out what is really needed. I n , ~ r u r l i u nI: State the P n h l ~ mThe . group usually decides thar the pn,blem is t o determme the kind irf fertilizer and the amount needed. Instruction 2: Define the Goal of the Project. Fertilizers replace elements lost from the soil. (Students are prodded in this direction through the initial reading assignment.) Instruction 3: Gather Information. The amounts of P.. N.. and K ,and possitdy othpr elements) to he replaced m a parttculnr fnrm nre calculated irum an elemental analyri, uf a rum crop. In/vrncol~o,z De,p 'l'hr arudrnta nrr given a lisr of borne chemicals, such as monoammonium phosphate, carried by the co-op store, and they are told that 6-10-6refers to an analysis as 6%N, 10%P205,and 6%K 2 0 . Instruction 4: Analyze Existing Solution. Amounts of N, P, and K supplied by 25 100-lb.sacks per acre are calculated and compared with amounts needed (from Step 3). Also costs are calculated. Instruction 5: Generate Possible Solutions. Each group member independently draws up a combination of available chemicals which will supply amounts of N, K , and P needed. An instruction to calculate the percentages of each element in the chemicals available may precede this step. Instruction 6: Determine Constraints. Criteria for a good solution are agreed upon-cost, possible health effects,and others. Instruction 7: Evaluation. Solutions generated in Step 5 are ranked aecordine" to the criteria from S t .e 6. ~. and an order of reference is agreed upon. (Students take prices directly from the "Chemical Marketing Reporter.") Instruction 8: Analysis. The group is asked why the better solutions ranked as high as they did. They are encouraged to calculate the amount of each necessary element that a dollar's worth of each chemical would buy. Instruction 9: Synthesis and Final Recommendation. Studentstry to improve upon their best solutions using the results from Step 8.
'
The idea for this oroiect came from a eeneral chemistrv texthook (5)which Geated agricultural chYemicals. The constraints in this nroiect are relativelv few. hut in eeneral there are several, and t h e groups may differ wi&y in their weightings. Several different final solutions are usually
reached, all defensible in light of the criteria and priorities used. At Polvtechnic a randomlv chosen a o u n of 30 students was divided &to five groups. A rotating group leader was assigned s for each nroied, . . . who took notes on the e ..r o u.~ ' deliberations and assembled a written report. A reading and problem assienment accomnanied each nroiect. In addition to usine a sgndard textbook (61, extensiveuse was made of the hakhashiri audiotapes (7). Competency-based testing was employed, allowing students to retake (similar) quizzes once or twice. Similar materials, assipnments. and testinn ~rocedures were used in a standard lecture class during the same semester. Five projects were completed in the term, covering the topics of atoms and atomic weights, gas laws and stoichiometry, thermodynamics, colligative properties, and solution equilibria. An example of the kinds of conclusions reached by different groups may he taken from the project on colligi~tiv~~ properties, in which the grnups were asked to rerommend a de-icing agent for city streets. The entire list ofchrmicals from the "Chemical Marketing Reporter" a n i available for their analyses. One rriterion they were asked specifically to consider u.as corrnsim. Some groups recommended NaCI, puttmi: cost first. Others felt CaC12 was more effertiw. and some included sodium carbonate to try to raise the pH and protect against corrosion. Ammonium sulfate was considered by some (but not finally recommended), since it is a product of garbage pyrolysis. Environmental criteria were also employed, and groups were encouraged to place costs on a dollars per degree of freezing point depression basis. The results after one semester were very encouraging, in particular with regard to drop rates. While 40%of the lecture section d r o.~.o e dthe course. none of the Guided Desien students did. The remaining studrnti in huth sertions took the same final exam.'l'he averaee was lower in the Guided Desicn section, as might perhaps have been expected, hut a slighGy larger percentage of Guided Design students passed the exam. A questionnaire was distributed to both sections. Lecture students disliked the course, did not feel they had learned much, and did not think that what they had learned had been worthwhile. Completely opposite sentiments were expressed by Guided Design students. Also, records from the Chemistry Learning Center, where audiotapes and other materials were kept, indicated three times heavier usage by Guided Design students (even after correcting for the 40%drop rate in the lecture section), even though the number of assigned materials was eauivalent. hea author will he pleased to supply a sample Guided Desien t interested Dersons. He would also like to ex- ~.r o.i e cto press his thanks to the ~ x x o nEducation Foundation for support of course development through a grant under the IMPACT program. Literature Clted (11 Wales, C. E.,and Stager, R. A,, Enginerrin8 Educ.. 62.456 119721. 121 Stager. R.A,, and Wales. C.E., Enrineering Educ., 62,539 (19721. 121 Tscng,M. S.,snd Wsles,C.E.,En8inashgEduc.. 62.812 11972). (41 Wales, C. E..Engineering Educ., 62,905 119721. (51 Andenon, C. B.,Ford. P. C., and Kennedy, J. H.."Chemistry: Principlesand Applications,"D.C. Heath, 197% 161 Brown. T. L.. and LeMay, H. E., "Chemistry: The Central Science: Prentice-Hall.
1977.
(71 Shakhsshiri, B. 2.. Sehreiner. R.,and Meyer, P. A,, "General Chemistry Audidape Lebrom"and"Workhuk for General Chemistry Audiotape Lesp~np:) W, B, Saunders, 1977.
Volume 57, Number 4, April 1980 1 299
