High School Laboratory without Lab Handouts Julie B. ~ a l ~ ' The Peddie School, Hightstown, NJ 08520
Miles Pickering Princeton University, Princeton. NJ 08544
An age-old problem of laboratory instruction is finding a way to get students to prepare before coming to lab. Recently one of the authors (MP) has advocated Yree form preparationn.The students may prepare their lab notebooks in any way whatever, subject only to the constraint that the lab manual not be brought into the room (1-4). Potentially this idea is a simple solution to the nagging problem of student preparation. However, there is still real skepticism about this idea, which has been tried only a t the college level in very few courses. This paper will examine what happens when this style of preparation is extended to a high school lab. Method The educational experiment to be described was conducted with 86 high school juniors taking chemistry a t The Peddie School, a private high school in Hightstown, NJ. The students were divided into two groups, both of which performed an experiment to illustrate conservation of mass in the formation of PbIz from KI and Pb(NOd2. Both groups received lab handouts the class period before the lab. Thc experimental group could prepare their notebooks in advance but not bring in the lab handout. The control groups were allowed to have the lab handout during the lab period. All students worked alone and recorded their beginning and ending times at various designated points in the lab procedure, so that the time requirements could be compared. The semester final exam taken by both groups contained several questions on the lab and also allowed the two groups to be compared for chemical knowledge. The lab questions asked the students to complete the word equation and the chemical equation. It also gave the students typical lab data and asked them to compute the ratio of reactants to products, a calculation done in the lab. Finally, students were asked to define conservation of mass and explain whether mass was in fact conserved, according to the data given. One person graded all of the lab questions on the exam and meticulous care was taken to see that the remaining parts of the exam were graded to identical standards. The results of this study are shown in the table. Results and Discussion The students in the experimental group were able to enter the classroom and begin the lab immediately, and they asked their peers and the teacher fewer questions about the lab than the control group. As a result, noise and confusion was reduced during the laboratory period. This suggests that the students seemed confident about what they were doing, at least at the operational level. No differenceswere observed between the control group and the experimental group on sections of the exam unrelated to the lab. This observation demonstrates that the 'Author to whom correspondence should be addressed. 150
Journal of Chemical Education
Comparison of New and Old Method of Lab Preparation Experimental Group
Control Group
40
46
Lab time (min)
36.4i 1 Oa
37.28 9.23
Grade on related exam question
15.8f5.22
13.93f 5.43
Grade on rest of exam
138.4i 29.9
138.8f 27
Number of students
+
'standard deviation two groups of students were matched. The experimental group's performance was better on lab-related questions, but the difference in performance was not of statistical s i g nificance. We conclude that the preparation method in the laboratory does not affect student understanding of laboratory principles. More puzzling is the fact that the time efficiencyof the students did not change. Kyle et al. have studied the distribution of student effort in laboratories and showed that Thus, if the about 12-15% is used in reading the book (5,6). students were better prepared, one might expect to see a decrease in time for the lab work. This factor does not appear to be true in this study. However, there are at least two ~ossibleex~lanations.First. another studv has shown ~ o t copying e that'the style okpreparation is important (21. of the book into the student's lab notebook leads to slower work than telegraphic summaries prepared in the lab notebook. Second, the studies of both Pickering and Kyle were done in college laboratories where the students could go home as soon as they finished, thus providing an incentive for working efficiently. While there are still unanswered questions about, "free form preparation," it seems to be a reasonable alternative a t the high school level. This new method of preparation does not damage understanding of laboratory principles in any measurable way, and also allows time previously used for explaining the experiment to be used for laboratory work or other teaching. Acknowledgment This work was supported by a n NSF grant (TPE8751837)administered through the Institute for Chemical Education a t the University of Wisconsin. The help of Frank Towne and Kim Samson of The Peddie School is gratefully acknowledged. Literature Cited 1. Piekering, M . J Coil. &i. Tehng lm,19,238. 2. Picketing, M. J . ChemEdue.1981,64,521. 3.Pieketing, M . J.Coll. Sci.Tehng 1988, 16, 187. 4. Picketing, M . J. ChemEdue. 1986.. 62.874. 5. Kyle, W C.;Ppnick. J.E.; Shymansky, J. A. J.&s 6. Kyle. W C.;Penick. J.E.;Shymmsky. J. A. J R r s
