Research: Science and Education edited by
Chemical Education Research
Diane M. Bunce
A Review of Laboratory Instruction Styles
The Catholic University of America Washington, D.C. 20064
Daniel S. Domin* Department of Chemistry, University of Wisconsin–Fox Valley, 1478 Midway Rd. Menasha, WI 54952-8002
Background The constructivist theory of knowledge states that knowledge cannot be transferred from one person to another; it must be actively constructed by the learner through interactions with the environment (1). Such a statement implies that the nature of the environment is as important as the characteristics of the learner when it comes to educating the individual, and altering the environment may lead to different learning outcomes. The environment can be operationally defined as those external influences that interact with the learner during the learning process (2). For simplicity, this article will limit the discussion of external influences to the general chemistry laboratory and the specific styles by which it is taught. Bloom has stated that curricular innovations are not “acts of faith” but rather new hypotheses, which should be empirically tested (3). Before systematic empirical evaluation of the different laboratory instruction styles can commence, a taxonomy must first be developed. The goal of this paper is to present a taxonomy of laboratory instruction styles and highlight the distinguishing features of each style. Throughout the history of chemistry education, four distinct styles of laboratory instruction have been prevalent: expository, inquiry, discovery, and problem-based. These styles can be differentiated by three descriptors: outcome, approach, and procedure (Table 1). The outcome of any laboratory activity is either predetermined or undetermined. Expository, discovery, and problem-based activities all have predetermined outcomes. For expository lessons, both the students and the instructor are aware of the expected outcome. For discovery and problem-based activities, usually it is only the instructor who knows the expected result. A dichotomy also exists for the approach taken toward the activity. Expository and problem-based activities typically follow a deductive approach, in which students apply a general principle toward understanding a specific phenomenon. Discovery and inquiry lessons are inductive; by observing particular instances, students derive the general principle. The procedure to be followed for any laboratory activity is either designed by the students or provided to them from an external source (the instructor, a laboratory manual, or a Table 1. Descriptors of the Laborator y Instruction Styles Style Expository
Descriptor Outcome
Approach
Procedure
Predetermined
Deductive
Given
Inquiry
Undetermined
Inductive
Student generated
Discovery
Predetermined
Inductive
Given
Problem-based
Predetermined
Deductive
Student generated
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handout). Inquiry and problem-based methods require the students to develop their own procedure. In expository and most discovery activities the procedure is given to the students. Expository Instruction Professor Expo wants her students to perform a laboratory activity that verifies the scientific fact, introduced in lecture and textbook readings, that heat can be released or absorbed during a chemical reaction. She also wants them to have practical experience in determining the amount of heat released by using the equation that relates heat flow to mass, specific heat capacity, and change in temperature. She has found just such an experiment in a commercial laboratory manual. It contains a pre-lab section with a detailed explanation of the chemistry the students will encounter, followed by a step-by-step procedure, a place to record data, and some post-lab questions.
The most popular, and yet the most heavily criticized, style of laboratory instruction is the expository (also termed traditional or verification) style. Within the expository learning environment the instructor defines the topic to be investigated, relates the investigation to previous work, and directs the actions of the students. The students repeat the teacher’s instructions or read the directions from a manual (4). The procedure the students follow is well stated so they may experience the predetermined outcome that is already known to both them and the instructor. The results obtained are typically used only for comparison against the expected result. As Pickering emphasizes, “[n]ever are the students forced to reconcile results, or confronted with challenge to what is naively predictable” (5). The traditional expository laboratory has been designed so that the activities can be performed simultaneously by a large number of students, with minimal involvement from the instructor, at a low cost, and within a two- to three-hour time span. It has evolved into its present form from the need to minimize resources, particularly time, space, equipment, and personnel (6 ). The predominant feature of the expository lesson is its “cookbook” nature, which emphasizes following specific procedures to collect data. Virtually no attention is given to the planning of the investigation or to interpreting the results (7). This manner of instruction has been criticized as placing very little emphasis on thinking (8), being an ineffective means of conceptual change (9), and being unrealistic in its portrayal of scientific experimentation (10). Tobin’s description summarizes these findings (11): Although teachers appear to value laboratory activities they did not implement it in the manner that facilitated the type of learning that was planned. …In most cases the laboratory investigation is intended to confirm something that has already been dealt with in an expository
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Research: Science and Education type lesson. Students are usually required to follow a recipe in order to arrive at a predetermined conclusion. As a consequence the cognitive demand of the laboratory tends to be low.
Analysis of expository laboratory activities as they are currently implemented suggests that virtually no meaningful learning takes place (12–14 ). Yet, in their review, Hofstein and Lunetta assert that laboratory activities have the potential to enrich the formation of science concepts by fostering inquiry, intellectual development, problem-solving skills, and manipulative skills (12). Two reasons exist for the inability of traditional laboratory instruction to reach its full potential. First, Stewart contends that in traditional laboratory instruction students spend more time determining if they obtained the correct results than they spend thinking about planning and organizing the experiment (15). Not enough time is allowed for them to actually think about the science principles being applied in the laboratory. That is, students are not afforded the time necessary for the deep processing of information. It is through deep processing that students are able to integrate new experiences with prior knowledge, establish a context for the purpose of the laboratory activity, and determine the activity’s relevance to themselves. All of which are characteristics of meaningful learning (16 ). Second, in their current format, traditional laboratory activities are designed to facilitate the development of lower-order cognitive skills such as rote learning and algorithmic problem solving. Bloom’s taxonomy of educational objectives is a hierarchical representation of six cognitive processes: knowledge (lowest), comprehension, application, analysis, synthesis, and evaluation (highest) (17 ). This classification scheme is often dichotomized into lower- and higher-order mental processes. Behaviors that would exemplify the lower levels of cognition include remembering, recognizing, or applying a learned rule. Higher-order thinking is exemplified by such behaviors as inferring, planning, or appraising. Domin conducted a content analysis of eleven commercially available general chemistry laboratory manuals and concluded that the majority of them require students to operate predominantly at the three lower levels of Bloom’s taxonomy, namely, knowledge, comprehension, and application (18). Virtually no activities require students to operate at any of the three higher cognition levels, analysis, synthesis, or evaluation. This is consistent with the results from content analyses of laboratory manuals from biology and physics (19–21). Inquiry Instruction Professor Inq is planning an open-inquiry activity, which introduces the students to a fundamental thermodynamic concept: heat flow. The students will be given the following assignment: Investigate the heat gained or lost for different systems. He expects this assignment to be vague enough that the students will have to decide the system to investigate, design their own experiments, and collect and analyze their own data. After the data have been analyzed and the students have made preliminary conclusions, Professor Inq will help them construct principles pertaining to heat flow.
An alternative to traditional laboratory instruction is an inquiry (or open-inquiry) approach. Inquiry-based activities 544
are inductive (22), have an undetermined outcome, and require the students to generate their own procedure. They are more student involved, contain less direction, and give the student more responsibility for determining procedural options than the traditional format (23). This approach effectively gives the student ownership over the laboratory activity (24, 25), which results in students showing improved attitudes toward science instruction (10, 26, 27). Inquirybased laboratory activities have also been found to improve students’ ability to utilize formal operational thought (28). Inquiry-type activities require the students to formulate the problem, relate the investigation to previous work, state the purpose of the investigation, predict the result, identify the procedure, and perform the investigation (4). It is through the process of devising plans that intellectual and pedagogic methods are united. Raths et al. (8) list the following higherorder thinking processes as components of inquiry: hypothesizing, explaining, criticizing, analyzing, judging evidence, inventing, and evaluating arguments. If done properly, the inquiry-based laboratory activity gives students the opportunity to engage in authentic investigative processes. The National Research Council describes inquiry as (29) A set of interrelated processes by which scientists and students pose questions about the natural world and investigate phenomena; in doing so, students acquire knowledge and develop a rich understanding of concepts, principles, models, and theories.
As reflected in the above statement, a popular notion exists among educators that inquiry instruction mimics scientific inquiry by placing the students into the role of junior scientists. Kyle, however, pointed out 20 years ago that inquiry instruction is not scientific inquiry, and we should make certain that our students understand the distinction between the two (30). Science is a full-time exploration for new, general, or applied principles (31). Students partaking in an inquiry-based learning activity are not only engaged in a process of learning the same concepts and principles that the scientist learned as a student, but are also learning the processes and methods of science. A particular outcome should be expected when learning science, but not when doing science (32). Even though research shows inquiry-based instruction to be extremely beneficial in promoting positive attitudes towards science and in fostering critical thinking, it has not been adopted extensively (8). A strong movement toward establishing inquiry-type instruction, especially in biology with BSCS and physics with PSSC (22), thrived in the 1960s. These attempts at curricular reform failed to achieve their anticipated goals of improved student understanding of science concepts; concrete experiences in carrying out scientific investigations; and the development of such inquiry skills as formulating hypotheses, designing experiments, performing observations and measurements, and drawing conclusions (33). Analyses of the inquiry-based projects of the 1960s revealed many explanations for their failure. Kohlberg and Gilligan believed that the inquiry activities “assumed formal operational thought rather than attempting to develop it” (34). Linn argued that the inquiry approach of the 1960s placed too much demand on the learner’s short-term memory by requiring students to simultaneously attend to new subject matter concepts, unfamiliar laboratory equipment, and novel problem-solving tasks (35).
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Content analysis by Herron (36 ), Tamir and Lunetta (19), and Lunetta and Tamir (37 ) found that the manner in which the inquiry-based activities were employed did not allow the students opportunities to practice and develop such important inquiry skills as defining a research problem, formulating hypotheses, planning an experiment, and identifying limitations. Duschl concluded that at the same time science education was adopting the perspective of teaching science as an “inquiry into inquiry”, the basic definition of inquiry was changing from only learning how to test knowledge claims to also explaining and evaluating these knowledge claims (38, 39). Other criticisms include placing too much emphasis on the scientific process and not enough on science content (40) and incorrectly equating scientific inquiry with unguided student discovery (41). Discovery Instruction Professor Disco is having her students perform a guidedinquiry activity that is intended to help them discover the concept of heat flow. Without any theoretical introduction, the students will follow a procedure provided by the instructor that tells them what to do and what data to record. They will collect their data and draw conclusions regarding the nature of heat flow. Through this experience and post-lab discussions, they will be guided toward discovering that during a chemical reaction heat can be released or absorbed, different materials possess distinct heat capacities, and the amount of heat a substance releases or absorbs is directly proportional to its mass, specific heat capacity, and change in temperature.
The origin of discovery (or guided-inquiry) laboratory teaching has been traced back to the early 20th century British science educator Henry Armstrong, who taught chemistry by a heuristic method in which students were required to generate their own questions for investigation (22, 32). No laboratory manual was used and the instructor provided minimal guidance. The student was placed into the role of discoverer. Discovery learning was also a basis of science education reform in the 1960s. Schwab argued that prior to classroom instruction students should partake of laboratory experiences in which the didactic laboratory manual be “replaced by permissive and open materials which point to areas in which problems can be found” (42). Bruner viewed the discovery method as “a necessary condition for learning the variety of techniques for problem solving” (43). Discovery learning is meant to personalize the information students acquire, making it more meaningful and better retained. The discovery approach, like inquiry, is inductive. By studying a specific example of a phenomenon, students are able to develop a general understanding of the underlying principle. Advocates of inductive learning emphasize both the value of learning by direct experience and the motivational value of “finding out for one’s self ” (32). Inductive activities are praised for bringing the undergraduate to the frontier of science (44 ) and for illustrating to the students the methods of science (45). Discovery (guided-inquiry) learning differs from inquiry (open-inquiry) learning with respect to the outcome of the instruction and to the procedure followed. Whereas in true inquiry instruction the outcome is unknown to both the instructor and the students, in a discovery learning environment the instructor guides the students toward discovering the
desired outcome. This is accomplished by giving the students directions for what they are expected to do. Discovery learning has received its fair share of criticism. Its most obvious disadvantage (shared with the other nontraditional forms of instruction) is that it is more time consuming than expository learning. The strategies of discovery learning also appear not to be transferable across disciplines (46 ). Hodson describes discovery instruction as not only philosophically unsound, but also pedagogically unworkable. “You cannot discover something that you are conceptually unprepared for. You don’t know where to look, how to look, or how to recognize it when you have found it” (32). Any activity that leaves the desired outcome open for discovery also leaves open the opportunity for it not to be discovered (46 ). In the same light, if the instructor points out the desired outcome, does this constitute discovery learning? It is also unrealistic to expect a group of students to simultaneously discover the same principle. More likely, as soon as one student discovers the principle of interest, the rest of the students will be given the information, much as in an expository lesson. Problem-Based Instruction Professor Prob wants his students to perform a laboratory activity that will help them better understand the concept of heat flow. The concept has already been introduced in lecture and in assigned readings from the text. The students will be asked to rank a series of chemical reactions according to the amount of heat given off on a per mole basis. He expects that the students have garnered enough information from the readings and lecture to design and implement a simple calorimetry-type experiment. Professor Prob will be on hand to answer questions and help students overcome any obstacles they may encounter. By attempting to solve such a problem, he expects that the students will better understand such concepts as endothermic, exothermic, and heat capacity.
Problem-based learning is becoming a popular alternative to the other three styles of laboratory instruction, not only in the general chemistry curriculum (10, 47 ), but also in other chemistry courses (48–51). It, however, is not a new manner of instruction. As early as the beginning of the 20th century Smith and Hall (52) described a method of laboratory instruction in which students were encouraged to apply their understanding of a concept in order to answer questions for which they had no answers. The instructor adopted a more active role by posing questions or problems to the students, providing the necessary materials, and carefully moving the students towards a successful solution to the problem. Problem-based learning was also a vehicle for curricular reform in the 1960s, albeit to a lesser extent than discovery or inquiry-based learning. Young, to encourage independent thinking, discarded the laboratory manual (53). Students had to create their own procedures to solve a problem and submit a written report describing the procedure, the results obtained, and the conclusions reached. Emphasis was placed on developing testable hypotheses rather than obtaining correct results. Although Young recognized some advantages of expository instruction over problem-based learning (clarity in teaching of principles and techniques, showing how the procedure fits the experiment, and increased student confidence), he also recognized that its applicability is limited (54):
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Research: Science and Education The student from the freshman year onward also needs opportunities to design his own procedures, if the challenges which can be given to him, which initiates his own investigation, is to be properly satisfied.
A similar style of instruction was described by Battino, in which there was no laboratory manual (55). Students took part in a pre-laboratory discussion where they participated in the design of the experiment. At about the same time, Cheronis was advocating a “philosophy of laboratory instruction” in which the students would carry out experiments of their own devising, applying learned facts and principles to novel situations (56 ). Cheronis emphasized that it is a complete waste of time “to expect a beginner before orientation and understanding of principles to perform a so-called research or problem-solving project.” A key emphasis in most college science courses is teaching students to be successful problem solvers. Unfortunately, as Stepien et al. point out, “[m]ost problem-solving programs present students with sterile heuristics,” which are frequently “considered more important than the problem the heuristic is meant to help solve” (57). In a problem-based learning curriculum, the methods of solving the problem are secondary to the problem itself. As in the real world, the problem comes first and serves as a vehicle for investigation and learning (57). In this style, students are presented with a problem statement often lacking in crucial information. From this statement they redefine the problem in their own words and devise a procedure that will lead them to a solution. The problems are “open-entry” (58). That is, they possess a clear goal, but there are many viable paths toward a solution. Wright emphasizes that the problems are designed to be conceptually simple (48), but there are enough details and enough unanticipated problems arise during the projects to provide students with many opportunities for creativity and practice in problem solving. In addition, the students struggle with course concepts in the contexts of a realistic problem, and this opportunity provides much greater insight into the course material.
Students working in a problem-based environment must apply their understanding of a concept to devise a solution pathway; this requires them to think about what they are doing and why they are doing it. Like discovery and inquiry-based instruction, problembased learning is time consuming and places a greater demand on both the instructor and the students than traditional instruction. Like inquiry instruction it fosters the development of higher-order cognitive skills through the implementation and evaluation of student-generated procedures. Problem-based instruction, however, is a deductive approach. Students must have had exposure to the concept or principle of interest before performing the experiment. Successfully completing a problem-based activity denotes an understanding of the concept. What the Research Says The beginning of this paper asserts that because each style of laboratory instruction affects the learning environment in distinct ways, differences should be apparent with respect to learning outcomes. To say, however, that any one of these styles of instruction is more effective than any other would be merely surmising. The paucity of necessary research makes any conclusion tentative at best. 546
For each of the three nontraditional styles of instruction, there are reports stating that students come away from the instruction with a better understanding of the material than they obtain from the traditional expository style (10, 59–62). The amount of credence one places on these findings is reserved for the reader. In no case did the authors perform a controlled study, or state how the assessment was made, or offer empirical evidence—other than student self-reports— to support their conclusion. A more controlled study to see if discovery learning has a positive effect on student learning relative to the traditional style was reported by Bodner et al. (63), who evaluated the effects of participation in either a discovery-style laboratory or a traditional laboratory on grades in a subsequent course. Citing a number of confounding variables that had to be considered, the authors chose not to formulate any conclusions as to which style, discovery or expository, results in greater student learning. A detailed study of the effects of laboratory instruction style on learning outcomes is that of Rubin, who performed a meta-analysis of comparisons between nontraditional approaches to introductory college-level laboratory instruction and the traditional approach (64 ). All the selected studies were conducted between 1970 and 1994, utilized valid statistical procedures in the data analysis, included a control, and addressed cognitive and/or noncognitive learning outcomes as a function of instruction method. The results of Rubin’s meta-analysis show that for the nonbiological sciences as a group (chemistry, physics, geology), nontraditional instruction styles can lead to significant improvement in student cognitive learning. However, when chemistry was examined independently, there was no significant improvement in cognitive student learning. Other studies, not part of Rubin’s meta-analysis, include that of Jackman et al., who compared a general chemistry laboratory taught using the learning cycle—a type of guidedinquiry—with the traditional verification style (65). The authors found no statistically significant difference between the two instructional styles in terms of student achievement on a posttest covering the learning material. Richardson and Renner (66 ) conducted a study that compared the effectiveness of applying inquiry to chemistry experiments relative to traditional instruction. They found that the inquiry group performed statistically better than the traditional group on the final laboratory exam. However, they did not define the term inquiry, and on the basis of the title of their paper, “A Study of the Inquiry–Discovery Method of Laboratory Instruction”, one is uncertain if open inquiry or guided inquiry was the style of instruction they examined. A study that does compare open-inquiry with traditional laboratory instruction was reported by Pavelich and Abraham, who measured gains in abstract thinking ability (67). Their results showed that the open-inquiry group made significant gains in abstract thinking ability compared with the traditional verification group over a single semester. Test results covering two semesters, however, showed no statistically significant difference in growth rate between the two groups. Holcomb investigated the effects the amount of direction within a chemistry laboratory activity has on the retention of learning (68). Two groups of students were given different amounts of direction for identifying unknowns in a qualitative analysis laboratory activity. Students given less direction performed significantly better on retention tests “provided
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that the learners were first grounded in the general principle in which the learning task was based.” Conclusions and Suggestions Through a review of the literature, this paper asserts that four distinct styles of laboratory instruction have been utilized throughout the history of chemistry education: expository, inquiry, discovery, and problem-based. Although the styles share many commonalities, each is unique and can be distinguished from the others by a set of three descriptors: outcome, approach, and procedure. It is assumed that these differences will lead to different learning outcomes. The establishment of a taxonomy of laboratory instruction styles, it is hoped, will provide the necessary impetus to initiate a research agenda that evaluates each style of instruction against the desired learning outcomes. To better understand the effectiveness of each style, researchers must go beyond comparing the general learning outcome, student achievement. Research is needed that addresses which style of instruction best promotes the following specific learning outcomes: • • • • • • •
conceptual understanding retention of content knowledge scientific reasoning skills higher-order cognition laboratory manipulative skills better attitude towards science a better understanding of the nature of science
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