|
Editor's Note: Reading about wonderful ideas for curricular
change is sometimes vastly different from making those changes work
in the classroom or laboratory. The authors this month describe specific
processes for change that have been used to introduce innovative learning
processes into their laboratory courses. In one case the content of
the course was not changed, but the timing was. In the second case
cooperative learning processes were introduced in order to facilitate
a change in the course content itself.
The most profound change to occur recently in the organic laboratory
course has undoubtedly been the introduction of mini and microscale
experiments (1). The introduction of microscale experiments
has been promoted in part by the reduced purchase and by the disposal
cost of chemicals, the decreased experiment time, and an increase
in safety (2). Some reluctance to implement microscale
experiments has been noted (1), but the microscale approach
has secured a considerable following as evidenced by regular articles
appearing in this Journal.
Over the past 10 years several innovative alternatives to the traditional
lecture have also been developed (3). Some of these alternatives
have been successfully extended into laboratory courses. Of the lecture
alternatives, cooperative learning has stimulated a considerable interest
particularly in the classroom (4) but also more recently
in the chemistry laboratory (5, 6). We have developed
a new laboratory program that uses cooperative learning and adopted
the program with a concurrent change from macroscale to predominantly
microscale experiments.
In this paper I describe how cooperative learning and microscale
experiments can be introduced concurrently and how the cooperative
learning environment may facilitate the introduction of these course
changes. This paper describes the process by which the course was
developed, key factors that enabled these changes to be introduced
smoothly, and an evaluation of the effectiveness of the new course.
Background
To facilitate the introduction of microscale experiments for
approximately 250 students, many experiments were screened in a smaller
laboratory course for students majoring in chemistry. Many of these
experiments had previously been carried out in the conventional macroscale
course, but several additional experiments were also examined. From
the more reproducible experiments, a lab schedule was designed that
incorporated predominantly microscale experiments and a few macroscale
experiments (nine and five in the fall, and ten and one in the spring).
This schedule was then used in a summer course and was positively
received by most students, especially those repeating the lab course.
The new schedule was then implemented in the regular academic year
with virtually no difficulties. The organic chemistry laboratories
at Duquesne are typically composed of 10-11 sections. Each section
is composed of approximately 25 students and is supervised by two
TA's.
Implementation
To effectively implement both cooperative learning and microscale
experiments all the TA's completed five half-day training sessions.
These sessions consisted of an introduction to cooperative learning
based on the strategies described by Johnson (4), followed
by modelling some group exercises. The TA's then carried out a typical
laboratory experiment in the revised format, giving them the student's
experience. The training in cooperative learning was designed to help
the TA's act as questioners or assistants of learning rather than
simply providing answers to problems.
Cooperative learning was fostered through a lab pretest (7)
and through group discussion facilitated by the TA's. Typically the
session began with a short lecture detailing the experiment and describing
any procedural modifications. This was followed by groups of three
students (assigned to the same bench for the entire semester) answering
questions related to both the experimental procedure and the chemistry
involved. These questions were culled from the typical kinds of mistakes
and misconceptions seen in the past and were designed both to test
students' comprehension of the experiment and to prevent common mistakes
from being repeated.
For example, students were asked the following questions during a
distillation experiment.
- Why are distillation apparatus always vented?
- Explain why the distillation apparatus is vented through a container submersed in ice.
- Explain why the first few drops of the toluene-cyclohexane distillate might be cloudy.
Superheating or uncontrollable bumping and bubbling often occurs when solutions are placed in new flasks and heated.
- a. Explain how superheating is usually prevented.
- b. How can superheating interfere with the distillation experiment?
The pretests were graded immediately, and any incorrect answers were
discussed with the group. Students were only allowed to begin the
experiment once their base group was familiar with the key experimental
details. Each lab was graded in three parts: the quiz (25%), the product
(25%), and the lab report (25%). The remaining points were assigned
at the end of the semester for lab technique.
Students had to carry out their own experiments, but they were encouraged
by the TA's to consult with group members throughout the session.
The group participation in the pretest was intended to establish a
cooperative environment that would facilitate further discussion during
the experiment. This student interaction was also facilitated by the
TA's through questions and changes to the experiment of one student,
who then explained this to the remaining group members. The extent
of this interaction is demonstrated in the results of the student
survey.
Questions Responses Yes No
1. The prelab questions have helped me identify 130 83 47
procedures that would have been detrimental
to the experiment.
2. I prefer the microscale experiments. 128 97 31
3. I prefer to work in a base group rather than 130 123 7
independently.
4. I often ask other base-group members for advice, 130 114 16
or check the procedure with them, during the lab.
5. I have met outside the lab period with my lab 130 35 95
base group to prepare for or write up the lab.
6. I have spent time studying with my lab base 129 31 98
group.
Evaluation
Late in the semester half of the students (130 out of 217) were
surveyed for their perceptions on the use of cooperative learning
in the laboratory course (see the table). For most of these students
this was the first course in which formal cooperative learning had
been encountered. A gratifying result from the survey was that the
majority of students found that the prelab questions helped identify
potential mistakes (question 1). This is particularly significant
because many accidents are a direct result of incorrect technique
or a lack of forethought. Most students preferred microscale experiments
(question 2), but almost a quarter of the respondents indicated a
preference for macroscale experiments. The balance between micro and
macroscale experiments in the current syllabus therefore seems to
be a good compromise between student satisfaction and training in
both techniques.
There is strong student support for using cooperative learning within
the course. Almost all students prefer to work with others (question
3), which may not be surprising because this is generally perceived
as improving an individual's grade. A better indicator may be that
most students (114, question 4) seek advice from other members of
their group during the lab. This group participation could also result
from building confidence among students who may otherwise feel intimidated
by having to complete an unfamiliar lab on their own. Another measure
of the effect of cooperative learning is given by the number (~25%)
of students who have met with their base group outside the lab period
either to study or for lab-related preparation (questions 5 and 6).
This number is surprisingly high, considering that most students were
placed in different base groups in the lecture course.
The transition from a macroscale lab course to a microscale course
can be difficult (1). By developing a pilot microscale
lab course and using cooperative learning as an integral aspect of
the lab experience, we have successfully implemented two significant
changes in the organic lab course. These changes were facilitated
when the students became accustomed to solving their difficulties
by working with others as a direct result of cooperative learning.
A controlled comparison of these changes was not pursued due to the
difficulty associated with implementing several changes simultaneously.
However, the student response has been favorable as seen from the
table and from student comments throughout the course. Several students
who enrolled in the summer course said that cooperative learning facilitated
their understanding and that they actually enjoyed the experiments.
Acknowledgment
The training of TA's was financially supported by a grant from the
Hunkle foundation. Support from the Duquesne University Department
of Chemistry and Biochemistry and the Center for Teaching Excellence
is also gratefully acknowledged.
Literature Cited
- Johnson, A. W. J. Chem. Educ. 1990, 67, 299-303.
- Williamson, K. L. Macroscale and Microscale Organic Experiment, 2nd ed.; Heath: MA, 1994; Preface, v.
- Schearer, W. R. J. Chem. Educ. 1988, 65, 133-136.
- Johnson, D. W.; Johnson, R. T.; Smith, K. A. Active learning: Cooperation in the College Classroom; Interaction: Edina, MN; 1991.
- Smith, M. E.; Hinckley, C. C.; Volk, G. L. J. Chem. Educ. 1991, 68, 413-415.
- Kandel, M. J. Chem. Educ. 1994, 71, 513.
- Curtis, G. D. National Teaching and Learning Forum 1994, 3, 10.
|
Citation
