The focus of this paper is on alternative conceptions in quantum chemistry held by honors students in high school. The study investigates how an intervention using interactive simulations in quantum chemistry alters student understanding. The researcher compares the effects of traditional methods of instruction, i.e. lecture/lab, against the use of discovery via computer simulation on the alternative conceptions of students in quantum chemistry. The researcher observed chemistry students in four high schools prior to, during, and after their use of the Quantum Science Across Disciplines (QSAD) materials which were developed at Boston University, through a National Science Foundation Grant.

Student concept maps, and interviews were used to find the baseline misconceptions of the student cohort regarding understanding of quantum science in chemistry. The high school students constructed concept maps and were interviewed after the intervention. The student information including concept maps were coded, and compared to the information obtained from students that exit a class using a more traditional approach. As a result of the intervention, high school chemistry students shift to a paradigm that uses the atomic or molecular explanations of quantum chemistry to explain macroscopic phenomena like polarity, and solubility.

Students in the experimental classes were required to investigate quantum phenomena using the simulations and then make presentations. Classmates were encouraged to ask probing questions. Several answers included molecular explanations using quantum chemistry to explain measurable phenomena. A Student began to use quantum science when explaining acid strength.

As a final example a student trying to explain bond length stated,

The teachers of the experimental and control classes used similar methods of assessment, while the teacher of the experimental classes used learning logs (Audet, 1996) during the units. For the learning logs, groups of three students were required by their teacher to achieve consensus and write a response to selected issues within quantum chemistry.

An investigation of the literature on alternative conceptions shows only minimal prior research on quantum chemistry. There is a study on student misconceptions for light and energy at the undergraduate level (Zollman, 1998) that points to confusion around the concepts of color, energy, intensity, and amplitude. The Bohr Model is often used in high schools as a simple way to explain bonding. Teachers do not explain to their students the shortcomings of the Bohr model with regard to the heavier atoms. Current high school texts include more abstract concepts, which are only useful if students adopt and apply them.

After conferring with the target high school faculty, the most difficult topic areas seem to be centered around the categories of phase, amplitude, molecular bonding, the lack of a localized phenomenon and, in general, connecting the concepts to other phenomenology.

The researcher divided this part of the study into three main areas expressed as questions: First, what preconceptions do students hold with regard to quantum science in chemistry? Second, what causes these preconceptions? Third, what can be done to minimize the impact that students' alternative conceptions have on student learning?

The researcher started with an outline which grouped the interview information into possible codes and larger categories. The outline was based on interviews conducted with three chemistry teachers from area high schools. Using the outline as a protocol for five student interviews, a complete list of fifty seven codes were generated. The concept mapping program C-map (Novak, 1989) was used to list the codes obtained from the interviews and then rearranged until they fit comfortably under eight categories: electronic structure, molecular geometry, bonding, periodic trends, polarity, solubility, energy, and color. After the main concepts were chosen, all related concepts were listed. Subsequent interviews and concept maps were focused on the eight main concepts with follow-up questions probing for student understanding of the relationships of the entire set of fifty-seven quantum chemical concepts.

A system of triangulation was used to check the codes that developed. Student concept maps were compared to an expert map derived from the eight categories found earlier in the preliminary interview process. Chemistry class test results from the target school showed the same areas of misconception prevailed. Student subjects and staff were shown the results as it accumulated. They agreed the conclusions were reasonable.

An expert concept map was produced by looking for other possible categories and then gradually reducing them into eight major concepts under the heading of atomic structure. Several rearranged listings of the concepts were used in order to decide what topics are the most closely related. One parent map with expert links and cross-links between the eight concepts was completed for comparison. It was important to observe whether students can link their basic molecular understanding to macroscopic events.

The researcher instructed each of the honors chemistry classes in the art of concept mapping prior to their study of the topic of quantum chemistry. Students were presented the categories to see what connections they could make. Four students, two male and two females, were chosen at random for in-depth interviews by the researcher. The interview allows the students an opportunity to present more elaborate explanations regarding their understanding of the material.

The teacher of the control group was instructed to proceed through the material in a normal manner. The experimental classes worked in groups of three on the computers studying electronic structure as explained by quantum chemistry including polarity as explained by charge density and bonding as explained by molecular orbitals. Teachers were instructed to assess their students in their normal manner. For the traditional class, this meant tests at the end of each chapter. It was interesting to note that the instructor of the control group was asked by the researcher about the laboratory exercises that were planned for the unit. The teacher stated, "There are hardly any lab activities for these units. After we do flame tests and mess around with spectroscopes, the rest of the activities are designed for the students to get extra practice studying the properties of gases. This year the gas labs were replaced by quantum chemistry activities"

The teacher of the experimental group had access to three computers in the classroom. The students were divided in half and were assigned to either work on the computers or write in their learning logs. The teacher presented them with questions that related to the computer investigation. These groups also worked on advancing their concept maps.

Student groups were required to write their thoughts regarding the relationship between quantum concepts and observable phenomena. One example is the group explanation for the color that is emitted by a gas discharge tube and the relationship to discontinuous spectra. Approximately 10% of the sample reported that the electron making a transition to a higher energy level is the cause of the color. Close to 30% of the sample continued to confuse the intensity of bright line with the energy of the color released.

A matrix was constructed containing the mistakes from a series of tests given by the chemistry teachers in the host high school. The columns are codes developed by the previous methods while information filled in the matrix holds the misconception. The areas that are dense indicate potential problem areas, while the sparse areas are either ones that the students understood or places where the questions might have been of a trivial nature. The following is the start of an outline developed for teachers at the host school. The purpose is to highlight student difficulties for the teacher. Examples of the misconceptions in the matrix follows:

A. Lewis structure: Student [8317] calculated the formal charge for BF3 as 9 for the whole molecule. Trying to put a double bond and indicate resonance where one is required, students sometimes miss that the metal empties its outer shell; therefore, looking to fill the octet does not apply.

B. VSEPR, valence shell electron pair repulsion: Student [8316] stated H2S is nonpolar while disregarding the fact that the unshared pairs of electrons bends the molecule and makes it polar.

C. Formal charge: Student [8312] calculated the formal charge for BF3 as 9 for the whole molecule. It is the individual items that we are trying to minimize. The benefit of formal charge is that it is a device for determining the best of a series of potential dot structures, and only one suggests itself with this molecule.

D. Three dimensional Vs two: Student [8311] OF2 drawn in two dimensions can look linear from one direction but is really bent from a perpendicular point of view. This same incorrect interpretation occurs when students diagram water (H2O) from the wrong point of view and somehow depth perception is lost.

In this study, students were allowed to make predictions about the macroscopic world based on their understanding of the microscopic. When the content is rich enough, students absorb themselves in study leading to the development of judgment in the area of scientific prediction. In chemistry, concepts learned in one unit become the foundation for the next. The mindful instructor needs to be alert to typical student errors before these misconceptions get in the way of further learning. Students investigated bonding and anti-bonding in the Diatomic Molecular Explorer prior to reading about them in the textbook. The teacher noted that students successfully used their information on molecular orbitals to predict why the formation of some bonds (e.g. He2) are not favored.

The science education literature has many references to the durability of student misconceptions in science. Novak points out that although it can be difficult to positively affect many alternative conceptions not all are intractable (Gabel, 1994). We have evidence that an interesting concept met with considerable resistance. It was noted by the researcher during the preliminary study that students often misinterpreted the signs on ions and also on energy values such as transition energies when a photon is released or when bond energies are evaluated. The symptom is manifested when students use a number line interpretation of the sign when evaluating endo- or exothermic situations. In addition, students were found to continually misinterpret the meaning of (+/-) for ions by adding electrons for plus and subtracting electrons for minus. Even after the instructor emphasized the correct analysis of each of these concepts 5-10% of the students continued to misinterpret the data.

The information gathered on student alternative conceptions in quantum chemistry will help to improve both curriculum content and teacher presentation. The findings of this effort are being used to refine the protocol interview for use with a broader set of quantum concepts after students use the computer simulations.

Audet, R. H., Hickman, P. & Dobrynina, G. (1996). Learning logs: A classroom practice for scientific sense making. Journal of Research in Science Teaching, 33 (2), 205-222.

Gabel, D.L. (1994). Handbook of research on teaching and learning. New York: Simon and Schuster and Prentice Hall International.

Hickman, P. (1994). Interactive-collaborative-electronic learning logs. Belmont High School, Belmont, MA.

Novak, J. D. (1989) C-map program: version 1. Ithaca: Cornell University.

Novak, J. D. & Gowin D. B. (1997). Learning how to learn. Cambridge: Cambridge University Press.

Zollman, D. A. & Rebello, N. S. (1998). Creating a modern physics course: visualization and computation for undergraduate physics majors. www.phys.ksu.edu.perg/vqm/working/mmprogrep.html#ideas

Zumdahl, S. S. (1993). Chemistry, Third Edition. Lexington: D.C. Heath and Company.