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. Re- cently one of the authors (MP) has advocated Yree form preparationn.The students may prepare their lab note- books 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 at the college level in very few courses. This paper will exam- ine what happens when this style of preparation is ex- tended to a high school lab.

Method The educational experiment to be described was

conducted with 86 high school juniors taking chemistry at 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 be- fore 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 dur- ing 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 equa- tion 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. Fi- nally, 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 ques- tions on the exam and meticulous care was taken to see that the remaining parts of the exam were graded to iden- tical standards. The results of this study are shown in the table.

Results and Discussion The students in the experimental group were able to en-

ter 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 con- fusion was reduced during the laboratory period. This sug- gests that the students seemed confident about what they were doing, at least at the operational level.

No differences were observed between the control group and the experimental group on sections of the exam unre- lated to the lab. This observation demonstrates that the

'Author to whom correspondence should be addressed.

Comparison of New and Old Method of Lab Preparation

Experimental Group Control Group

Number of students 40 46

Lab time (min) 36.4 i 1 Oa 37.28 + 9.23 Grade on related 15.8f 5.22 13.93 f 5.43 exam question

Grade on rest of 138.4 i 29.9 138.8 f 27 exam

'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 ig nificance. We conclude that the preparation method in the laboratory does not affect student understanding of labora- tory principles.

More puzzling is the fact that the time efficiency of the students did not change. Kyle et al. have studied the dis- tribution of student effort in laboratories and showed that about 12-15% is used in reading the book (5,6). Thus, if the students were better prepared, one might expect to see a decrease in time for the lab work. This factor does not ap- pear to be true in this study. However, there are at least two ~ossible ex~lanations. First. another studv has shown that'the style okpreparation is important (21. ~ o t e copying 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 incen- tive for working efficiently.

While there are still unanswered questions about, "free form preparation," it seems to be a reasonable alternative at 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 an NSF grant (TPE-

8751837) 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. JRrs

150 Journal of Chemical Education