liquid would float on a lake. I assumed that the students would reference the density of water and then
answer the question. However, one student proceeded to experimentally observe that the liquid did float on
water and used the results in her answer. In another case, using the double burrette apparatus, one third of
a class started to use the equipment to back titrate, a common practice for those with titration experience but
one that had not been used by these freshman chemistry students. In both these instances the students
adapted the experimental equipment to formulate a new attack on a problem, building on their base of
experience.

I believe the laboratory practicals to be effective, acceptable and in most cases a proper alternative to the ©
present practice of written exams in most science course laboratories. The laboratory practical provides a
final that measures the skills learned in the laboratory. It separates those who know the procedures from
those who have depended on partners or their neighbors.

Student response has also been positive. In my most recent class, 72% stated that the exam was fair.
About half of those who stated it was fair also said that it was frustrating and rushed. This response
indicates to me that the exam does push students to their limits (frustrating and rushed), but the students
have confidence in their ability to obtain answers. In general, those students who come prepared for the lab
and make an effort to achieve in the lab do well on the exams. The students who state that it is unfair are
generally those who do well on the paper-pencil exams as opposed to the application portions of the course.

Some Sample Laboratory Practical Grade Distributions

General Chemistry Chemistry for

Non-Sciences Majors
Scores Frequency Scores Frequency
<-64 0 <-64 XXX
65-69 XX 65-69 XXXXX
70-74 x 70-74 XXXX
75-79 XXXXXX 75-79 XXX
80-84 XXXXXXXXAXXXAXXXAXKXX 80-84 XXXXX
85-89 XXXXXXXXXXXX 85-89 XXX
90-94 XXXXXXXXAXXXKX 90-94 XXXXX
94-> 0 94-> xX
Totals 52 29

It is my contention that the laboratory practical is a realistic and appropriate exam for science laboratories.
It tests directly the skills and knowledge that are to be developed in the laboratory. It tests skills that one
assumes are being developed but are not tested in any other situation. And it is not redundant inasmuch as
it does not test the same skills as the lecture exams.

Frank Plucker
University of Arizona

For further information, contact the author at the University of Arizona, 327 Education Building, Tucson, AZ
85721.

 

 

Suanne D. Roueche, Editor
November 13, 1987, Vol. IX. No ?6

INNOVATION ABSTRACTS Is a publication of the National Institute for Staff and Organizational Development, EDB 348, The University of
Texas at Austin, Austin, Texas 78712, (512)471-7545. Subscriptions are available to nonconsortium members for $35 per year. Funding in
Part by the W. K. Kellogg Foundation and Sid W. Richardson Foundation. Issued weekly when classes are in session during fall and spring
terms and once during the summer.

“ The University of Texas at Austin, 1987
Further duplication Is permitted only by MEMBER institutions for their own personnel. ISSN 0199-106X