An Investigation of the Value of Using Concept ... - ACS Publications

Research: Science and Education edited by

Chemical Education Research

Diane M. Bunce The Catholic University of America Washington, D.C. 20064

An Investigation of the Value of Using Concept Maps in General Chemistry Gayle Nicoll,*† Joseph Francisco, and Mary Nakhleh Department of Chemistry, Purdue University, West Lafayette, IN 47907; *[email protected]

Science in general has traditionally been very hard for students to understand. Several people have attributed this difficulty to students’ lack of connections between concept areas (1). For instance, chemistry textbooks are traditionally divided into units, which are further divided into chapters. While this helps to organize the material from a textbook standpoint, it may also hamper students’ connections and further learning. Indeed, several people have noted students’ lack of connections between content areas (2). Concept maps have been proposed as a means to facilitate students’ formation of links between content areas (3, 4). They are potentially powerful tools to effect conceptual change in the classroom (5, 6 ). Because concept maps are a very visual method of helping students to organize their own thinking, they appeal to a different type of student than do other organizational methods, such as outlines. Concept maps have been hailed as a powerful tool for helping students link together material in disciplines such as biology (7) and math (8). While concept maps have been used in chemistry courses before (9–13), their use was limited to holistic assessment or as a teaching tool. Research has found a relationship between concept mapping and student achievement (14 ), and it is worthwhile to determine whether students exposed to concept maps throughout their general chemistry course do, in fact, make more connections between concepts than students not exposed to concept maps in this way. Although the effectiveness of concept maps as a teaching tool has been established (7, 10), we did not find any reports of whether the integration of concept maps into a chemistry course actually facilitated a more interconnected understanding of the material. Therefore, we attempted to assess the degree to which students in a general chemistry course for science and engineering majors linked related concepts. We compared students in two sections of the course: in one section concept maps were an integral part of the course and in the other they were not. We chose the concepts of electrons, bonding, electronegativity, and molecular geometry for this research. These topics not only form the basis for further understanding of chemistry, but they are also often taught as discrete concepts, which may leave the students the task of integrating the material. This paper describes the results of a qualitative inquiry to determine to what extent students linked these topics together as a function of whether they were actively exposed to concept maps in their course work. † Current address: Department of Chemistry, Hamilton Hall, University of Nebraska, Lincoln, NE 68583.

Participants Participants were volunteers from the freshman-level general chemistry course for science and engineering majors (CHM 115) at Purdue University. Twenty volunteers were interviewed for the study. Ten students (control group) were from CHM 115M, a section in which concept mapping was not part of the curriculum; and ten (treatment group) were from CHM 115A, a section in which concept maps were an integral part of the course. All students who participated in this course were traditional college students. While every attempt was made to balance the treatment and control groups with respect to gender, only two men from the treatment section volunteered. Thus, there were eight women and two men in this group, whereas there were five men and five women in the control group. Among the controls, one male had not had any high school chemistry, seven students had taken one year of high school chemistry, and the other two had taken two years. In the treatment group, five students had taken one year of high school, four had taken two years, and one female had taken three years of high school chemistry. Three minority students were included in the study. The study was limited to ten students from each section of CHM 115 so we could focus on students’ depth and breadth of knowledge. Had more students been included, we could not have developed such a detailed picture of each student’s understanding of these concepts. Since one of our goals was to determine how interconnected students’ maps were, we decided to perform a qualitative study in order to capture a more detailed and accurate representation of students’ links. While this limits the generalizability of the findings, it was a useful strategy for this investigation. Course Design The professor who taught the treatment section of CHM 115 used concept maps in lecture, during recitations, and on exams and quizzes, whereas the professor who taught the control section did not employ concept maps at all. Students in the treatment group used concept maps for the entire course, not just for the topics dealing with electrons, bonding, geometry, and electronegativity. Students were trained at the beginning of the course in their recitations in constructing concept maps. Afterwards, they constructed concept maps as part of their homework assignments and quizzes. They also worked in groups during recitations to construct concept maps and the professor presented concept maps during lectures. Students’ concept maps on quizzes and homework were evalu-

JChemEd.chem.wisc.edu • Vol. 78 No. 8 August 2001 • Journal of Chemical Education

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Research: Science and Education

ated by their teaching assistants, and students received feedback on these. Except for the use of concept maps, the courses were essentially the same. The professors for both sections used traditional lecture techniques in a large lecture hall setting. Enrollment for the course is usually around 400 students per section. The exams were multiple choice and the two professors agreed upon the questions together so that both sections took the same exam. Since the syllabi for these sections were identical, the sections themselves were equivalent, the only differences between them being the professors who taught them and the use of concept maps. We do admit that different professors tend to have different teaching styles, which may have influenced the study, but every attempt was made to minimize this effect. Thus, we can compare the concept maps of these two sections, which in all other aspects were essentially the same. In this manner, we determined whether the exposure to concept maps affected the way in which students organized their understanding of the concepts of bonding, electronegativity, electrons, and molecular structure. Procedures One of us (GN) conducted qualitative interviews once toward the end of the semester after the instructors had covered the topics of bonding, electrons, electronegativity, and geometry according to the course syllabus. This was done so that students presumably had had the opportunity to link the concepts taught during the course of the semester. Each student was given an individual, private, hour-long interview. Field notes were made after each interview to record impressions, observations, and trends coming out of the interviews. These field notes became part of the data. An open-ended, semistructured interview style was adopted to allow students to express their ideas as fully as possible. Students were not asked to draw concept maps during the course of the interview. Rather, the interviews were recorded and concept maps were constructed from the transcribed interview data. While students in other studies were usually allowed to construct their own concept maps, it has been shown that concept maps can also be reliably generated from student interviews (15–18). Requesting students to generate their own concept maps within the context of the interview would have had several drawbacks for this study. Students would have needed training to generate concept maps, which would have required more of their time. More importantly, we sought to determine what links students had already constructed between topics. Requesting students to generate concept maps might have been a direct intervention in their learning, causing them to generate links that did not previously exist, as a result of having to think about the material in terms of a concept map. Our semistructured, open-ended interview protocol yielded a more accurate representation of what the students knew and had linked together, although it was still possible that they cemented their understandings as a result of the interview. However, by not having students construct concept maps during the interview we avoided the problem of new links being generated by the act of constructing the map and thus preserved the students’ organization of the material as much as possible. In addition, the interview format permitted a more accurate and 1112

full representation of students’ links to all associated concepts, whereas having students generate concept maps as part of the interview would have limited the number of concepts they were allowed to link. Therefore, we used a technique similar to that in previous research (17 ) to interview students and subsequently generate concept maps for analysis. The interview probed students’ understandings about electronegativity, bonding, and molecular structure. It was broken into five main questions. The first dealt with chemical bonding and was designed to elicit terms that students associated with this concept. It helped to focus students on the topic that the rest of the interview would deal with while simultaneously probing what the term “chemical bond” meant to them. Students were asked probing questions based on their responses, to clarify their answers. Probing questions asked students to define terms they had used in answering the first question. Probes were also used to attempt to elicit more detailed or coherent responses. The second question required students to take their understanding of chemical concepts one step further by drawing the Lewis dot structure of formaldehyde. Formaldehyde was chosen for several reasons. It is a relatively simple molecule that freshmen-level general chemistry students should be able to draw correctly. However, it contains more than two elements, so students have to think about the connectivity within the molecule. It also contains a double bond, which makes it a more difficult problem for less experienced students. Finally, based on how the students draw their Lewis dot structure, there are a variety of geometries that they might predict for the molecule. For example, although the molecule is trigonal planar, students who do not realize that there is a double bond may state that the molecule is pyramidal. Students had to think about how to draw the Lewis dot structure of formaldehyde, explain their drawing to the interviewer, and predict the geometry of formaldehyde on the basis of their Lewis structure. Students were given only the chemical formula of formaldehyde (COH2) and a periodic table. In the third question, students were asked to use Play-doh to build their own model of a molecule of formaldehyde. They were given four colors of Play-doh so that they could choose how they wished to represent the atoms. They were also given sticks of two different lengths, which they were told they could use if they wanted to. This gave the students flexibility, as they could choose to build a space-filling representation without sticks, or they could designate the short sticks as double bonds and the long sticks as single bonds. Regardless of the representation they chose, they had to explain why they built the model the way they did and what the individual parts of the representation meant to them. This question was designed to probe how students had the concepts of bonding and molecular geometry linked and how they used these links to solve this simple chemistry problem. The fourth question concerned microscopic representations. Designed to probe students’ mental models of molecules, it required students to describe what a single molecule would look like if they could see down to that level. In asking the question, the interviewer also probed students’ understanding of molecular phenomena related to electron motion, intermolecular forces, and bonding. For instance, students were asked, “What’s happening to the molecule?” to determine whether they believed that the molecule, individual atoms,

Journal of Chemical Education • Vol. 78 No. 8 August 2001 • JChemEd.chem.wisc.edu


and/or the molecular bonds were in motion. If students did believe that the molecule was in motion, they were asked to explain why it was. Students were free to interpret what phase the sample was in. If they mentioned different phases, they were asked follow-up questions to determine how their microscopic picture would change on the basis of phase. The final question probed students’ “ultramicroscopic” representations, or what they believed was going on inside the molecule. It was designed to determine how students conceptualized orbitals, bonding, and electron motion at the microscopic level. Specific probing questions were asked to determine whether students had a solar system model of an atom and whether they believed that electrons are in motion. Concept maps were generated by the analyzers from the transcripts of the interviews (for an example, see Fig. 1). All names used in this paper are pseudonyms. Once the skeleton of the concept map had been drawn for each student, the maps were assessed using the 3-tier coding scheme for concept maps (19) to reflect the complexity of each student’s understanding of the material. The 3-tier scheme focused on the connections students made between nodes and analyzed the concept maps on the basis of each link’s stability, usefulness, and complexity.

For reliability, one concept map generated from the interviews from each section was randomly selected and given to three analyzers, who independently generated concept maps from the transcripts (16 ). These were to be drawn on the basis of the preestablished conventions for generating concept maps. The maps generated by the second and third analyzers were compared to those of the original analyzer by counting the number of similar nodes and links in order to calculate a value for the inter-coder reliability; this was determined to be 0.74 overall and was deemed acceptable for this study, considering the complexity of the concept maps involved. Results and Discussion To ensure that the groups were comparable, the grades that students self-reported were used to determine an average GPA for each section of CHM 115. The average GPA for students in CHM 115A (treatment) was 2.4 and that for CHM 115M (control) was 2.2 on a 4-point scale. A t-test to determine if there was a significant difference between these two samples indicated that at an α level of .05, there was no difference between these two sections (t = 0.36). Thus it is possible to draw comparisons between the two samples of students.

Key Useful

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Figure 1. A concept map generated from the transcript of the interview with Frederick, a freshman in the control section of CHM 115.


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Figure 2. A concept map generated from the transcript of the interview with Judy, a freshman in the treatment section of CHM 115.

Concept Map Data Table 1 contains a summary of the data from the concept maps for the volunteers from both sections of CHM 115. The total number of links (propositions connecting individual concepts) ranged from 21 to 117 and the total nodes (or concepts) ranged from 23 to 79. Table 1 lists the average number of total nodes, floating nodes (unconnected concepts), total links, useful links (correct connections), emerging links (tentative connections), wrong links (incorrect connections), and incomplete links (correct but not comprehensive con1114

nections) for the two sections of CHM 115. Note that the number of floating nodes did not differ significantly between the two sections, nor did the number of incorrect, emerging, and incomplete links. This was important, because it allowed a fair comparison between the total number of links based on the number of useful, and hence correct, links. The concept maps of the treatment students were significantly more developed than those of the control students in terms of the total number of links (t = 2.27, α = .05), total number of nodes (t = 1.85, α = .05), and total number


Research: Science and Education Table 1. A Comparison of Treatment and Control Concept Maps Concept Map Feature Total nodes Floating nodes

Average Number Treatment (N = 10) 49

Control (N = 10) 38

t 1.85*

1.6

2.3

Total links

69.9

46.2

Total useful links

55

34.6

2.4*

2.4

0.38

Emerging links

2.2

0.82 2.27*

Wrong links

8.4

6.5

0.75

Incomplete links

6.5

5.1

1.28

*Significant at the α = .05 level.

of useful links (t = 2.40, α = .05). This is illustrated by Figures 1 and 2, which are examples of concept maps generated from interviews with students enrolled in the two sections of CHM 115. These data may indicate that integrating concept maps into the course of the general chemistry curriculum helped students to connect the concepts. That students in the treatment group had significantly more total nodes than control students would indicate that they were acquiring more concepts overall than control students. Treatment students also had significantly more total links than controls. However, the total number of links includes incorrect links as well as correct ones. If students in the treatment group had more total links only because they were incorrectly linking the material, this would not be a favorable reflection on using concept mapping as a teaching tool. Therefore, a more interesting comparison of students’ concept maps is the total number of useful links. Treatment students had significantly more useful links than the controls, a further indication that they were more correctly integrating these concepts from different domains into their knowledge structures than were control students.

Qualitative Coding Scheme Data The qualitative coding scheme revealed that the types of links made by treatment and control students were very similar, but there are interesting differences. For instance, eight students from the treatment group and nine students from the control group had links between the concepts of electrons and bonding. While it appears at first that there is no difference between the two groups, looking further at the qualitative data revealed that the eight students in the treatment group had almost twice as many examples of electron–bond links (70) as the nine controls, who only had 40 examples of electron– bond links. This indicates that although both groups are linking these concepts, the treatment students are interconnecting the material more often than the controls. Similarly, six treatment and four control students made links between the concepts of bonding and electronegativity. There were 45 examples of the bond–electronegativity link within the treatment group and only 14 from the control group. Once again, this indicates that the treatment students who do make the connections are integrating the concepts more thoroughly into their knowledge structure than are the control students. Although students in both sections make

the bond–electronegativity link, those in the treatment group make more, and more diverse, links between these concepts. Moreover, the frequency with which the treatment students mention the link between bonding and electronegativity or the link between electrons and bonding indicates that these links are very active and readily accessible, since the students were able to access them multiple times during the interview. They were also able to use these links in multiple settings to solve different types of chemical problems. For instance, Tara, a student enrolled in the treatment section, first mentioned electronegativity in the first question of the interview, when she was asked to explain what chemical bonding is: It’s to do with the electronegativity of the atoms that’re being shared, depending on how strong the pull is from one atom or the other will depend on whether they’re shared or they’re actually transferred.

Later on, when Tara was asked to explain what electronegativity is, she first provided a definition and then went on to add: But if it’s greater than something, then it’ll be ionic, and less than that it’ll be covalent. Just because the stronger the pull is, the more likely they are to be actually transferred as opposed to where they’d just be shared.

Thus, while these quotations all show examples of a link between the concepts of bonding and electronegativity, they also demonstrate that Tara has multiple types of links within this group that she felt comfortable using. Not only did she link the idea that electronegativity has to do with the sharing or transfer of electrons in bonds, she also linked electronegativity with the difference between ionic and covalent bonding. Both of these quotations are therefore coded in the electronegativity– bond group, although they have subtle but important differences, which allow for a richer and more diverse set of links that students can draw upon to solve problems in chemistry. Two of the students from the treatment group, Bridgette and Meiko, made links between the concepts of bonding and geometry, whereas none of the controls did. The link between bonding and geometry was deemed more complex than other links because students who made it could solve more difficult chemical problems. For instance, because of Bridgette’s link, she was able to explain how to determine the geometry of a molecule based on the number of bonds it has: ’Cause double bonds are, well, they’re stronger and shorter [than single bonds], you know, and they’re harder to break. … But when it comes to, like, the formation of, like, shapes and stuff, it really doesn’t impact, impact that much.

Here Bridgette has not only demonstrated that she understands that there’s a difference between the strength of double and single bonds, but she has also indicated that she realizes that double bonds still count as only one entity when determining the geometry of the molecule. This is an important concept for freshmen; several other students in the study made the mistake, for instance, of claiming that formaldehyde’s geometry should be tetrahedral because it had 4 bonds. The link between bonding and geometry appears to be difficult for students to make in the first place. Therefore, the fact that two students in the treatment group were able to make the link while none of the controls could do so appears


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important. This seems to indicate that more treatment students than controls are making the connection between these concepts. The interview transcripts revealed examples of how students from both sections of CHM 115 used their links to predict and solve chemical problems posed to them in the course of the interview. For seven treatment students and nine controls there were definite examples of how they used their links in this way. While this suggests no difference between the groups in ability to predict and solve problems, the seven treatment students were able to use their links more frequently to solve problems (95 examples) than the nine controls (69 examples). This indicates once again that students in the treatment group who do make the links are able to use them more effectively than the control students. The types of problems the students were able to solve seemed to depend on the types of links they made in the first place. For instance, Bridgette, from the treatment group, was able to satisfactorily explain how lone pairs affect the geometry of a molecule: It’s because the two lone pairs of electrons have higher energy levels or, they’re, like, stronger. Like, they want more space, you know. And, and so they push these guys, the bonded pairs down because bonds are less energy, they’re, like, they’re happy and they don’t need that much space.

Because of this link, she was able to predict the geometry of molecules. In contrast, Alex, a student in the control group, could not explain the phenomenon of electron movement once he mentioned it: “I can’t explain, but I don’t remember why. …But, yeah, they’re just constantly moving around. I’m not sure why. Can’t answer that.” Alex never mentioned lone pairs or how they could affect molecular geometry. It should be noted, however, that the coding of how students used their links to solve chemistry problems was not limited to correct examples. Since our goal was to determine how students used their links to solve chemical problems, this necessarily included how they used incorrect links. Bridgette’s examples also showed how she used her incorrect Bohr conception of the atom to explain the representations of bonding in water: I just switched it kind of in my head as I was, like, “Okay, well, the Bohr model’s not quite right, but” because there’s 8 [electrons in the Bohr model], there’s 6 [electrons in p orbitals]. And then on this 3rd ring instead of, for the electron you have, instead of, like, 8 [electrons] there’s 10 for the p orbital. Even though there might, you know, they build. They also add up and stuff.

It’s clear from this excerpt that Bridgette doesn’t have a correct explanation of how the orbitals in oxygen are arranged, but it was the tool she used to explain the representation. All 10 students in each section of CHM 115 revealed instances of a lack of links between concepts. In fact, a lack of links between concepts was generally very prevalent. This not only comes through in the qualitative coding but also in the field notes, where the investigator noted multiple instances of students’ failure to make connections between concepts. As an example, after the interview with Arthur, a B student from the control group, the field notes stated: 11/30/98: Arthur was another 115 student. I’ve noticed that those students who get F’s certainly don’t have much in the way of links, but those getting A’s seem to fall into 1116

two categories: those that really understand the material (and have lots of links) and those who memorize material to pass the exams (and have very few links)! I think this is really interesting! Arthur fell into the second category. He couldn’t explain much of the “why” behind anything.

The field notes bring up an interesting observation: that while almost all of the students who were receiving F’s in the course had very simplistic concept maps, those who were getting higher marks, A’s and B’s, did tend to fall into two categories. This is seen in the concept maps: some students who were getting high grades had very complex maps, whereas others had relatively simplistic ones. This suggests that some students only memorized terms and information in order to pass the exams. Such students would make few links or have poorly developed concept maps. Indeed, Arthur stated, “But, I mean, usually, like, if, if I learn something like that, or like this, like, I’ll know it for the test and then I’ll just forget about it, basically.” Keep in mind that Arthur was a control student who was receiving a B in the class. Summary The data from both the qualitative coding and the concept mapping reveal a significant difference between the two sections of CHM 115. The sections were equivalent except for the innovative use of concept maps throughout the course in CHM 115A (treatment). The significant differences in the concept maps of the groups appears to be attributable to the use of concept maps during instruction in the treatment group. Although the small sample size in this study renders these conclusions tentative and further research will be necessary to validate them, our findings are consistent with recent content work by Taber (20). There were significant differences in the number of total nodes, total links, and useful links. In every case, the treatment students’ maps had significantly more nodes and links than control students’ maps. These data suggest that the treatment students were making more complex connections between concepts than the controls. Because other factors were controlled for and the two groups had comparable GPAs, we interpret these data to mean that the use of concept maps in the treatment course facilitated the linking of concepts. This indicates that the use of concept maps as an integral part of students’ course work (including homework, quizzes, recitation problems, and exams) is equipping students with a powerful learning and study tool. The introduction of concept maps into the course appears to have facilitated the making of more links and has allowed students to hang more concepts onto their existing concept maps. Apparently, as a result, these students have more complex maps and are therefore able to solve more complex problems than control students. Literature Cited 1. Gilbert, S. W. Student Knowledge of Models and Science: Some Findings and Relationships; Presented at the 61st annual meeting of the National Association for Research in Science Teaching, Lake of the Ozarks, MO, April 10–13, 1988; ERIC ED292667. 2. Cliburn, J. W. Jr. J. Coll. Sci. Teach. 1990, 19 (4), 212–217. 3. Cohen, D. J. Curriculum Supervision 1987, 2, 285–289.


Research: Science and Education 4. 5. 6. 7. 8. 9.

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Heinze-Fry, J. A.; Novak, J. D. Sci. Educ. 1990, 74, 461-472. Wallace, J. D. J. Res. Sci. Teach. 1990, 27, 1033–1052. Hynd, C. R. J. Reading 1991, 34, 596–601. Novak, J. D. Instruct. Sci. 1990, 19, 29–52. Malone, J.; Dekkers, J. School Sci. Math. 1984, 84, 220–231. Feldsine, J. E. Proceedings of the 2nd International Seminar: Misconceptions and Education Strategies in Science and Math, 1987, Vol. 1, pp 177–181. Fowler, T. W.; Bou Jaoude, S. Ibid., pp 182–186. Ross, B.; Munby, H. Int. J. Sci. Educ. 1991, 13, 11–23. Schreiber, D. A.; Abegg, G. L. Scoring Student-Generated Concept Maps in Introductory College chemistry. Presented at the Annual Meeting of the National Association for Research in Science Teaching, Lake Geneva, WI, April 7–10, 1991; ERIC ED347055. Regis, A.; Albertazzi, P.; Roletto, E. J. Chem. Educ. 1996, 73,

1084–1088. 14. Stensvold, M. S.; Wilson, J. T. Sci. Educ. 1990, 74, 473–480. 15. Boschhuizen, R. Eur. J. Teach. Educ. 1988, 11 (2/3), 177–185. 16. Nakhleh, M. B.; Krajcik, J. S. J. Res. Sci. Teach. 1993, 30, 1149–1168. 17. Pendley, B. D.; Bretz, R. L.; Novak, J. D. J. Chem. Educ. 1994, 71, 9–17. 18. Shavelson, R. J.; Lang, H.; Lewin, B. On Concept Maps as Potential “Authentic” Assessments in Science; National Center for Research on Evaluation, Standards, and Student Testing, U.S. Department of Education: Washington, DC, 1993; Grant #R117G10027; ERIC #ED367691. 19. Nicoll, G.; Francisco, J. S.; Nakhleh, M. B. A Three-Tier System for Assessing Concept Map Links; Int. J. Sci. Educ. (in press). 20. Taber, K. S. Int. J. Sci. Educ. 1998, 20, 597-608.


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