Learning in Chemistry with Virtual Laboratories

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Teaching with Technology

Gabriela C. Weaver

Learning in Chemistry with Virtual Laboratories

Purdue University West Lafayette, IN 47907

P. Martínez-Jiménez,* A. Pontes-Pedrajas, and J. Polo Department of Physics, Ed. C-2, Campus of Rabanales, Córdoba 14071, Spain; *[email protected] M. S. Climent–Bellido Department of Organic Chemistry, E. Politécnica Superior, Córdoba 14004, Spain

Important changes in teaching chemistry have occurred in recent years (1–3). Research on learning processes and difficulties in this subject (4) has shown that many teaching models lack effectiveness in the transmission of concepts. New didactic intervention models have been formulated to improve chemistry education (5, 6). In addition, there has been an extensive development of new information technology, which has exercised marked influence on education by facilitating the design of new teaching materials. These materials have improved the attitudes of students toward chemistry and advanced interactive and collaborative teaching and learning processes (7, 8). Many studies (9–11) have shown the usefulness of computers in science education: as an interactive communication means permitting access to all kinds of information (texts, images, different types of data, graphics, etc.); as an instrument for problem solving; as a tool for carrying out simulations of chemical phenomena and experiments; and to measure and monitor laboratory experiments (12, 13). It should also be noted that computers can be used to administer and direct class tasks, to store and analyze educational process data, to carry out learning evaluation, and to diagnose deficiencies and propose remedial activities (14). Computers began to be used in education a few decades ago with great expectations. However, the results have not been as good as was anticipated. At first, computers were used as program-teaching aids, based on behaviorist theories, but this did not prove to be very satisfactory. Later, computer applications in education were greatly extended and, in most cases, a technological–educational model was adopted. It was assumed that the learning process could be enhanced as the means and procedures for presenting the information continued to improve. However, extensive research on alternative concepts and learning difficulties has suggested that a constructivist approach to science education, which propagates an all-round learning of science, is a better model (15). This educational perspective can also be transferred to the computer-assisted teaching field. To be specific, some articles have underlined the interesting possibilities offered by computer programs to promote the understanding of concepts by means of conceptual-change processes (16, 17). We believe that computers can be used in other activities, such as designing experiments and solving problems, which are also of great educational value in chemistry. In the constructivist approach to science teaching these activities can be conceived as investigation processes (18). By applying this idea to the educational–technology area, we believe that the computer can be used as an instrument to analyze students’ previous knowledge of a topic, help the students propose their 346

own hypotheses with regard to a problem, make a selection between several possible solutions, analyze results, draw conclusions, and so forth. Thus, the computer can be a tool for helping students to be active participants in their own learning process (19, 20). From this perspective, our research has focused on the development and evaluation of a tutorial system that includes several modules (assessment of previous knowledge and ideas, problem solving, simulations, self-evaluation, etc.). From an educational point of view, the main didactic utility of this tutorial system is that, when compared to other methods and other teaching aids, it offer simulations of chemical phenomena in which the student can modify the independent variables of the problem and analyze how the remaining variables change (21). We believe that experiment and process simulation is one of the most interesting activities among computer applications in science education. Computer simulations are constantly improving as the graphic capabilities and processing speed of computers increase. Educational-type simulations permit the presentation of situations that, in practice, are irreproducible; the idealization of experimental conditions; the presentation of situations requiring very complex equipment; the presentation of dangerous processes; and the manipulation and control of variables. In addition, simulations can be low-cost alternatives to the real processes (22–24). The development of virtual chemistry laboratories also has relevance to computer chemical applications in the treatment of a broad spectrum of problems of educational interest (25–27). Considering the various aspects of multimedia resources in chemistry teaching, especially related to this research, two aspects should be emphasized. Firstly, use of appropriate educational software can improve the performance of students carrying out practical work in the laboratory, as has been demonstrated in previous research (28–29). Secondly, the important role of the activities done by the students should be emphasized as they use multimedia resources in their understanding of scientific concepts and procedures, as has been shown in several theoretical (30) and empirical (31) studies. This indicates that it is necessary to combine the use of virtual chemistry laboratories with the activities aimed at encouraging thoughtful learning in students during practical laboratory work (14). Educational Content and General Goals The teaching environment at the University of Córdoba is challenging. The introductory courses are overcrowded (pupil:lecturer ratio is approximately 150:1) and it is not pos-

Journal of Chemical Education • Vol. 80 No. 3 March 2003 • JChemEd.chem.wisc.edu

Information • Textbooks • Media • Resources

sible to give lecture and laboratory classes simultaneously. Thus the class is subdivided into groups of 30 students for participation in the laboratory. In addition, the lecturer finds it impossible to individually tutor students. The instructors need additional tools to maintain a quality program. Over the years, our research team has developed computer tools for numerical simulations for solving problems in physics and chemistry. These programs have been used as supplementary teaching aids in traditional lessons (21, 27). Our results have demonstrated that students’ conceptual understanding and problem solving ability improved (24). Based on these results, we decided to conduct an educational project involving the development, application, and evaluation of a virtual chemistry laboratory (VCL), which involved basic step-by-step laboratory procedures and simulated real laboratory activities (32). The goals of the project are as follows: •

To relate the theoretical–practical aspects of chemistry teaching, since students have access to the conceptual information in the tutorial

•

To know the instruments and processes necessary to understand the phenomena studied in each experiment

•

To improve the self-learning process of students and encourage the acquisition of scientific skills in the experimental activities

•

To ensure that students learned how to use important apparatus in a chemistry laboratory

•

To critically analyze the experimental results on comparing the VCL data with those obtained in real experimentation

To achieve these ends, we reviewed the results from previous evaluations of chemistry laboratory students. We then developed a program of activities specifically to help students overcome conceptual and procedural learning difficulties (observed in prior evaluations) and to direct student work in simulated experiments. The educational experiment was conducted with engineering students. However, lecturers in other subjects (such as chemistry) have shown an interest in this program so in the near future we anticipate data that will enable us to compare results across different populations of students.

The software fosters integration and interactivity. Integration is achieved by including all the functions to be carried out in the learning process in one program. Interactivity allows users to decide the course of their learning process at each moment and they are able to modify the experiment being done in the simulation. The program consists of four different yet interconnected modules: tutorial, VCL, evaluation, and a section allowing instructors to create their own tests. Even though each module can be carried out independently, it is advisable to follow the above order, at least in the initial use of the software. A detailed description of each module of the software was given in a previous work (32). However, a brief description of the modules will be given so that the reader can get a clearer idea of the program’s features.

Tutorial Module In this module, different concepts and basic principles of chemistry are explained by means of hypertext used for illustrating and animating tutorials. The knowledge acquired by the student in this module will be used and reinforced in the VCL module. These tutorials are accessible from any point in the software using the general index, and students can repeat this module as often as necessary (Figure 1). In the theory section, students find a menu to choose the subject to study by clicking the corresponding button or by selecting the appropriate hot key. Each time students return from one of these subjects, the theory menu changes slightly, showing a small check mark above the button of the subject to indicate that the subject has already been studied. VCL Module This module is the most interesting from an educational point of view. It allows students to perform simulated chemical experiments (following an activity program guide) to obtain results similar to those obtained in a real laboratory. There is a work screen in which the students can access three interactive areas to consult relevant information, perform experimental procedures, and observe the evolution of the experiment.

VCL Description The software used in the experiment was developed in a Windows environment, using a multimedia programming tool (Microsoft VB 5.0). The CD, including the executable version of this program, has been published by the University of Córdoba (32), so that anyone interested in a more detailed description can consult the user’s handbook. The program can be used on a individual computer or through a local network; it is also distributed via the Internet at the University of Córdoba’s Web page, http://www.uco.es/grupos/ labvirtual (accessed Nov 2002). The software includes installation disks and a workbook. A Windows 98 operating system, or higher, is required. All the application screens have similar features and interfaces that are as intuitive as possible to minimize navigation difficulties in the program. Nevertheless, there are support screens showing the meaning of the controls and access to each screen is assisted with an audio explanation.

Figure 1. Tutorial module with help screen.

JChemEd.chem.wisc.edu • Vol. 80 No. 3 March 2003 • Journal of Chemical Education

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Firstly, it is possible to access a library of materials (Figure 2) or apparatus used in the VCL to simulate each experiment. All the materials are classified depending on their nature and an image of each of the materials is shown, together with text specifying its use. This section could be considered a dictionary of the materials used in chemistry laboratories. It has been designed so that students can access it from any other part of the application, allowing them to consult it at any moment. Secondly, students can access a section of basic laboratory operations. In this screen, the student can visualize the basic processes needed in a chemistry laboratory that are essential for the further development of chemistry experiments. For example, this module illustrates solutions from commercial reagents (solids and liquids), distillation (normal and at a reduced fractionated pressure), extraction (liquid–liquid and solid–liquid, at ambient temperature, reflux, and continuous), and filtration (by gravity and at reduced pressure). Vertical buttons show the materials needed for each basic operation. Once a selection has been made, the material can be moved to the working screen where it acquires the dimensions needed. With the horizontal quick-access buttons, apart from the usual operations of any application (i.e., File→ New, Open, Print, etc.), students can establish the initial conditions, for example, type and purity of the product. By doing this, the operation is visualized and the numerical results needed (namely, proportions, concentrations, and so forth) are obtained. Links to other programs, such as calculator and word processing, allow students to quickly open practical exercises provided by the lecturer to guide students in the selflearning process. In the third area, several usual practices in chemistry, such as obtaining caffeine from tea leaves, are demonstrated using animation. In this area previous knowledge gained from the tutorial is used, the laboratory can be visualized, and numerical results can be obtained. Students visualize the procedures by means of step-by-step animations as if they were performed in a real laboratory. As shown in Figures 3 and 4, the experiment is set up by students dragging materials and reagents from the bar on the left of the screen to the work table. The necessary data for the selected task has to be entered previously.

Evaluation Module In this module, a multiple-choice test is available to evaluate the students’ content knowledge and also to enable the students to continue to learn during the work sessions in the virtual laboratory. Students select this module activating a test composed of questions that can be determined by the instructor. The questions usually appear one-by-one with different levels of difficulty. The program evaluates the answers and gives students the score obtained, using graphs to indicate the percentage of correct, incorrect, and unanswered questions. Testing Module Instructors who have access to the testing module by means of a password and subsequent identification have the option of making new questionnaires or modifying existing questionnaires. The possible options of this section allows instructors to create files, include figures, print exams, and so forth. 348

Figure 2. VCL module library of materials screen.

Work Methodology A program guide of activities directs the students’ interactive work and encourages an active and thoughtful learning process (14). This program guide can be regarded as an additional document in a Windows environment or as a written document. The first activity consists of accessing the evaluation module of the VCL and answering questions posed in the program. The results of this initial evaluation are intended to identify areas of subject-matter weakness; students are encouraged to review relevant material before proceeding. After that, a general review of the VCL program’s tutorial module should be conducted in order to answer different questions, such as: What are the main advantages of a reduced fractionated pressure distillation? Does it have any disadvantages? What is meant by a concentration of a solution and how can the concentration be expressed? The third general activity composed of a large set of specific tasks consists of accessing the VCL module and virtually performing an experiment, following the steps proposed by the program, and answering the questions posed on this subject. Sample questions from the extraction of caffeine from tea experiments could be: Why is it necessary to mix tea leaves with water and boil this mixture? After heating the initial mixture a solution containing tannic acids and caffeine is obtained; what new chemical substances should be used and what process must be followed to achieve the precipitation of the tannic acids in this solution? What has to be done to obtain pure caffeine before having the final distillation? Where is this substance collected and in what physical state does it appear? After completing this program and the practical activities, students are advised to go back to the evaluation module and answer new questions to evaluate the concepts they were supposed to acquire during the work session. Finally, students are asked to think over the results of the final evaluation and to draw their own conclusions on the software’s educational value. For instructors using this program, the greatest didactic interest lies in the development of the third activity, in which students are invited to reflect on and analyze what they ob-



Figure 3. Intermediate step in setting up distillation.

Figure 4. Distillation procedure.

served in the simulation, and, at the same time, to follow the steps proposed by the software (see examples of steps 9 and 14 in Figures 3 and 4, respectively).

ties were similar. A comparative study of the results from the control and experiment groups was made from the data obtained by using several evaluation methods. Assessment of the learning process of basic chemistry laboratory techniques in the control and experiment groups were taken throughout the academic year when the experiments had been completed. In this paper, the assessments obtained from one experiment, the extraction of caffeine from tea, were analyzed and compared. To conduct the study of the control groups, the laboratory experiment was prepared, providing the students with theoretical information and a document outlining the tasks to be carried out. The educational content developed in this first study can be broken down into the following three sections: laboratory apparatus (glass, metal, etc.), basic operations in the chemistry laboratory (preparation of solutions, distillation, filtration, extraction, etc.), and experiments involving basic processes (extraction of caffeine from tea leaves, etc.). At the end of the experiment, students handed in a written report in which they analyzed the results and drew conclusions and answered diverse questions related to their interpretation of the processes performed in the laboratory. Finally they were asked to complete an evaluation in the form of a written questionnaire, in which several questions relating to the understanding of the above concepts and procedures were posed. With the experimental groups, the same experiment was repeated, using the VCL as a complement. The educational content regarding the concepts and procedures of the experiment process were the same as those carried out in the control groups. GE1 and GE2 worked in small groups during several sessions, first with the virtual laboratory and then in the real laboratory. Advantages of using VCL include repeating an experiment simulation as many times as necessary and consulting the evaluation module to identify gaps in understanding the relevant material. Students followed the VCL program instructions: they dragged the icons of the laboratory material window to the simulation window, entered data on the experiment’s quantitative variables, selected the type of basic operation to do at each moment, observed the results of the successive pro-

Evaluation of the Educational Experiment

Experimental Design of the Research Our research goal was to discover whether using the VCL program as a complement to traditional teaching methods improved student performance in a laboratory experiment. To find this out we compared the results of a control group— using traditional methods—with the results of an experimental group—using traditional methods and VCL—using statistical analysis to reveal any differences in performance between the groups. To better clarify our research goal we identified four subgoals: •

To learn about the characteristics of important chemistry laboratory apparatus and to acquire skills in the setup and operation of practical exercises

•

To master the basic operations performed in a chemistry laboratory

•

To acquire the necessary knowledge to select the appropriate techniques to solve mixture separation problems

•

To relate the theoretical–practical aspects proposed with those experiment tasks

To assess the achievement of these subgoals, the software program was used with first-year technical-engineering students for a period of two years. In the first stage, data were taken from two groups of students who followed a traditional teaching method based on theoretical exposition and experiments in the laboratory: control group GC1, n = 72, and control group GC2, n = 67. In the second stage, data were taken from two other student groups who had been taught the same theoretical–practical content using the VCL as a complementary tool to introduce them to the real laboratory: experiment group GE1, n = 65, and experiment group GE2, n = 70. The age and grades of both groups did not show any statistically significant differences, so it can be assumed that the students’ prior knowledge and learning abili-


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cesses, taking notes on the latter, and discussed the questions posed in the activity program guide. After working with the software, students from the experiment groups did the same experiments as the control group students, with the advantage that the procedures needed to carry out this work were already familiar to them. The time devoted to the experiment was similar in both groups as the students substituted the theoretical approach used in the control group with the VCL in the experimental group. Both groups of students wrote reports on the work done in the laboratory.

periment. Statistical processing was done on the differences observed in the performances. With the data corresponding to the scores on the four objectives obtained from both groups, various tests were made to analyze whether the differences between these groups were statistically significant. Since the quantitative data considered in this study did not fulfill the restrictive conditions of the statistical parameter tests, we applied the Kruskal–Wallis test.

Analysis of Results To evaluate the results for each objective, four levels of learning were established according to the following classification: level I corresponded to very low scores—deficient learning; level II corresponded to average scores—fair or semiacceptable learning; level III corresponded to high scores— good learning; and level IV corresponded to very high scores—very good learning. Students’ results were categorized by level of learning. This classification enabled us to present the results of each objective in tables that can be easily interpreted. Table 1 shows the results obtained by the students in the control groups, GC1 and GC2, corresponding to the evaluation of the four objectives (1, 2, 3, and 4), allocated to the learning levels (I, II, III, and IV). The percentages corresponding to each level established for each objective and group are shown in columns. From Table 1 it can be seen that the results for both groups are similar. On comparing the results from GC1 and GC2 in each of the four objectives, it was observed that there were some differences in the levels, but the statistical contrast study made among the average scores of each group showed no statistically significant differences in any of the objectives. We inferred that both groups had developed a similar learning process and had reached a similar performance level. In both groups it was observed that levels III and IV showed much lower percentages than levels I and II, so we deduced that the amount of knowledge acquired by the control groups was not particularly good, although it can be considered as acceptable according to percentages reached in level II for each of the four objectives. The same evaluation and analysis process were followed for the experimental groups. Table 2 shows the results ob-

Evaluation of the Experiment An evaluation was made of the understanding acquired by students in the control and experiment groups. Evaluation focused on assessing the performance in the following areas, corresponding to the four research subgoals cited above: 1. Skills in setting up the experiment and the actual success of the experiments 2. Quality of the laboratory reports drafted by students at the end of the experiment, in which the results obtained from the experiment and the answers to the questions posed in the work guides were shown 3. Results of an experiment in which a practical problem was proposed, for instance, the separation of mixtures, for which students selected an appropriate technique 4. Results of a written test made up of several questions in which students demonstrated that they can relate the theoretical–practical aspects involved in the study

The evaluation process was the same in both the control and experiment groups. To assess the level of learning a global numerical grading system (0–10 points) was adopted to quantify the data from objectives 1–4 listed above. Additionally, to evaluate the individual performance of each student, the points corresponding to the four objectives were summed so that each student received a score between 0 and 40 points. Overall learning levels were defined from the points, and it became possible to develop some conclusions from the ex-

Table 1. Evaluation of Learning Objectives in the Control Groups Learning Levels

Objective Results in GC1 (%)

Objective Results in GC2 (%)

1

2

3

4

1

2

3

4

I

37.5

29.2

36.1

33.3

41.8

22.4

29.8

46.3

II

40.3

45.8

47.2

44.4

32.8

34.3

43.4

34.3

III

13.9

15.3

9.7

16.7

20.9

26.9

17.9

16.4

IV

8.3

9.7

6.9

5.6

4.5

16.4

9.0

3.0

Table 2. Evaluation of Learning Objectives in the Experiment Groups

350

Objective Results in GE1 (%)

Learning Levels

1

I

15.4

2

Objective Results in GE2 (%)

3

4

1

2

3

4

9.2

18.5

29.2

12.8

14.3

25.7

28.6

II

23.1

20.0

41.5

46.2

22.9

27.1

37.1

40.0

III

44.6

47.7

29.2

20.0

47.1

38.6

24.3

22.8

IV

16.9

23.1

10.8

4.6

17.2

20.0

12.9

8.6



tained by the students in these groups. The results obtained by both experiment groups also present a similar allocation of percentages to the different levels. Moreover, in the statistical contrast study made among the average scores of each experimental group, no statistically significant differences were noticed in any of the objectives, not surprising since both groups had the same characteristics in the beginning, had carried out a similar study process, and had reached a similar performance level. In order to analyze the influence of the methodology used in the experiment groups, a comparison was made of the results of the experimental groups (Table 2) with those previously obtained by the control groups (Table 1). In this comparative analysis, there were several interesting facts. For instance, on analyzing the data of the first and second objectives, it was observed that the percentages in levels I and II were much higher in the control groups than in the experiment groups, which suggests a shift in the number of students from groups GE1 and GE2 who had achieved these objectives compared to those who had not succeeded in groups GC1 and GC2. Likewise, on applying several statistical contrast tests, significant differences were noticed between the average values of the scores obtained in objectives 1 and 2 in the experiment groups versus the control groups. This led us to conclude that the use of the software, together with the laboratory experiments, had helped to improve the knowledge about the apparatus and basic operations in the laboratory in the experiment group of students. With regard to objective 3, the comparative analysis in Tables 1 and 2 showed that the results were also better in the experiment groups than in the control groups, so it can be concluded that the use of software combined with the real laboratory facilitated the development of the procedures and skills necessary for the solving practical problems of mixture separation. In the third objective, the statistical contrast of the average scores of these groups was not as sharp as in the previous objectives, but it also supplied statistically significant differences in the experiment group. Tables 1 and 2 allow an analysis of the results of objective 4, which is related to the answers to theoretical–practical questions on the aspects dealt with in the development of the experiment. In this case, relatively similar results could be seen in all four groups, characterized by the existence of higher percentages in the lower performance levels (I and II) than in the higher levels (III and IV). In the analysis of the average scores for objective 4, no statistically significant differences were observed between the different groups, with the except of group GC2, which demonstrated a lower performance than the other groups due to the high percentage of individuals catalogued in level I. Groups GE1, GE2, and GC1 have similar results; these results could mean that the use of the VCL either did not have significantly different influence on the groups with regard to the development of this objective or that the questions posed had the same degree of difficulty for these groups. Finally, we evaluated and categorized the performance of each student from the different groups. To elicit an overall score for each student, the points from the four objectives were summed resulting in a overall score between 0 and 40 points. Following the same procedure, four performance levels were established: LI—overall score between 0 and 10

Table 3. Performance Levels of the Control and Experiment Groups Groups Results (%)

Performance Levels

GC1

GC2

GE1

GE2

LI

31.9

34.2

18.5

20.1

LII

41.7

43.4

30.8

32.9

LIII

13.8

11.9

33.8

31.4

LIV

12.6

10.5

16.9

15.6

points indicating deficient learning; LII—overall score between 10 and 20 points indicating semi-acceptable learning; LIII—overall score between 20 and 30 points indicating a good level of learning; and LIV—overall score between 30 and 40 points indicating an optimal or very good learning result. Table 3 shows the results of the four groups, with the percentages of the four performance levels in each group. Firstly, it can be seen that the control groups GC1 and GC2 had very similar results in the four levels. The results of the experiment groups GE1 and GE2 were also similar, although these groups present a better overall performance than the control groups. Indeed, the control groups showed a higher percentage in levels LI and LII with respect to the experiment groups (with variations of close to 15% and 10%, respectively). In level LIII, the experiment groups obtained much better results than the control groups (with differences of over 20% between these groups). Finally, in level LIV, all the groups reached similar, although low, percentages, which indicate that there were some difficulties in achieving an optimal performance level by all groups. From a statistical point of view, the overall scores of the four groups (with a Kruskal–Wallis test) lead us to infer that, under conditions of overcrowded classrooms, little tutoring, and the inability to correlate the theory and practical classes, the VCL favors the training of the average student as it causes a shift in the results from the grades of deficient and acceptable to good in the experiment groups. Finally, we believe that the similarity in the results obtained in level LIV was due to the fact that in all the groups there were a few students with a higher level of specific knowledge and a greater interest in the subject that performed well regardless of the teaching methodology.

Summary of Results Some facts worthy of remark can be deduced from these results: 1. The evaluation process obtained similar results in the two control groups, GC1 and GC2, so that the research methodology used can be considered reliable. 2. Similar results were observed in the experiment groups, GE1 and GE2, using the same evaluation method, so the learning process can be considered to be homogeneous. 3. Significant differences were noticed between the degrees of progress of the experiment groups with respect to the control groups. The greatest differences were seen in level I (deficient learning), notably much greater in the control groups, and in level III (good learning), notably higher in the experiment groups.


351


From these observations, it can be concluded that the instruction process followed in the experiment groups enabled students to achieve a higher level of learning than in the control groups and that the VCL program used is helpful in improving the learning process. This would appear to confirm the results obtained in other studies that show the favorable influence of the use of simulation programs in the teaching of chemistry (28, 29) and of other sciences such as physics (31). Final Conclusions and Considerations From the empirical educational research presented, we conclude that the use of a VCL program is beneficial to students. Students showed a better comprehension of the techniques and basic concepts used in their laboratory work. Use of VCL especially contributed to improving the work of those students who have the greatest learning deficiencies. The use of the VCL as a learning aid that complements the traditional method has the following advantages: •

It permits the reflective self-training of students throughout their individual work, either as a clarification and complement to experiment laboratories or as a practical task in itself.

•

The problem of overcrowding in the lecture halls can be addressed, especially in the introductory courses (150–200 students per lecturer).

•

It allows instructors to focus on the explanation of basic theories and reduces the time devoted to instrument operation and technique.

Although we consider the results of this study to be positive, it should be noted that whereas studies on the evaluation of chemistry educational software (33–35) have been analyzed, no specific research of this type dealing with the concepts and procedures conducted in this experiment have been found, so it has not been possible to establish comparisons with other work. Therefore, until other studies support our research, the results shown in this article can only be considered as provisional, not general or definitive. Acknowledgments The authors are grateful to Gerardo Pedrós Pérez for his help and constant support during the preparation of the manuscript. We are also indebted to Dolores Calzada for suggestions and comments, and to Diana Badder and José Juan Caballero Valero for reviewing the English. Finally, we would like to convey our appreciation to four reviewers and the Teaching with Technology Editor for valuable comments, questions, and suggestions. Literature Cited 1. Robinson, William R. J. Chem. Educ. 1998, 75, 282. 2. Brooks, D. W.; Liu, D.; Walter, L. J. J. Chem. Educ. 1998, 75, 123.

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Learning in Chemistry with Virtual Laboratories

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