Article pubs.acs.org/jchemeduc
Development of a Web-Based, Student-Centered Stereochemistry Tutorial Nicola J. Burrmann*,† and John W. Moore Department of Chemistry, University of WisconsinMadison, Madison, Wisconsin 53706, United States S Supporting Information *
ABSTRACT: A Web-based stereochemistry tutorial is described that details the core definitions and structural representations of stereochemistry in an organic chemistry course. The Cahn−Ingold−Prelog rules and their application for assigning R and S orientations to stereocenters and E and Z orientations to alkenes are discussed. This tutorial is unique in allowing students to determine their preferred structural representation of organic molecules and select their own method for making stereochemical comparisons between these molecules. The remaining content of the comparison section of the tutorial is presented using the method that the student selected.
KEYWORDS: Second-Year Undergraduate, Organic Chemistry, Internet/Web-Based Learning, Stereochemistry, Student-Centered Learning
O
way or have equal levels of spatial intelligence necessary for proper comprehension of stereochemical concepts.1,8 Spatial intelligence involves a combination of visual memory, visual imagination, and mental processing of this visuospatial information.1,3 Not all students are at ease working with R and S assignments or with visualizing molecules written in the instructor’s or textbook author’s preferred method.8,11 Even if students are comfortable with a particular notation, they are often uncertain about how to transform other molecular structural types into their preferred representation.3
rganic chemists primarily think and communicate through drawings, using reactant and product structures and other symbols to illustrate chemical transformations concisely.1−3 Two-dimensional, pictorial representations of molecules, drawn either on paper or using electronic programs, are often used instead of three-dimensional models. Twodimensional pictures are simple to produce quickly and are often easier to disseminate than three-dimensional models, especially as molecular size increases. As a result of this heavy reliance on drawings, organic chemical thinking is often less “logical-mathematical” than “logical-visuospatial.”1 However, conveying this visuospatial knowledge to students is often difficult because many students lack a strong foundation in three-dimensional visualization.4 This difficulty is especially pronounced in organic chemistry courses, in which students must apply three-dimensional analysis to molecules drawn in two dimensions.5 In translating between two- and three-dimensional representations of molecules, students typically make step-by-step changes until the conversion is complete. However, many students are unable to visualize molecular shapes properly, and one or more steps in this process fails.2,3,6 Because of these factors, stereochemistry is one of the most difficult concepts of organic chemistry for students.4,5,7−10 Student confusion is often compounded by the course instructor’s or course textbook’s presentation of the rules and concepts of stereochemistry.3 Instructors typically use the R and S method, as determined by the Cahn−Ingold−Prelog rules, on molecules written using wedge−dash notation or Fischer projections to determine stereochemical relationships.4,5,7,8 Additionally, not all students learn in the same © XXXX American Chemical Society and Division of Chemical Education, Inc.
■
RATIONALE FOR WEB-BASED APPROACH It is unfortunate that instructors or textbooks have insufficient space and time to present all of the possible methods for determining the stereochemical relationship between molecules because individualized teaching tools are highly effective and allow students to make unique personal connections between new concepts and previous knowledge.3,8 Individualized instruction on visuospatial concepts has been shown to improve chemistry performance.3 Using the Internet as a medium for creating an instructional tool would allow for more individualized instruction because the Internet is not subject to the space limitations of a printed textbook. Although traditional textbooks can reasonably print only a limited number of pages on any particular topic, mainly due to cost considerations, the amount of “space” available for production of a Web-based tutorial is limited only by the size of the server used to host the tutorial. This makes the Internet a prime
A
dx.doi.org/10.1021/ed300744s | J. Chem. Educ. XXXX, XXX, XXX−XXX
Journal of Chemical Education
Article
medium for presenting material geared toward individual learning methods, as each method can be presented in its entirety. Ultimately, quality of explanations does not have to be sacrificed due to constraints on quantity of available space or cost of production. A 2006 report by the Pew Internet & American Life Project showed that 84% of people between the ages of 18 and 28, a range that encompasses the ages of typical college students, go online. Furthermore, 73% of these users conduct school research online. 12 Students who incorporate computer technology into their schoolwork are often more interested in learning and find their assigned tasks more “fun” relative to those who use more “traditional” media, such as textbooks, for learning.1 In particular, the use of computer molecular modeling in an upper-level high school class was instrumental in clarifying spatial relationships between molecules.1,3,13 Students enjoy the ability to interact with the subject of their learning through a medium with which they are familiar, namely, computers. Prior to beginning this work, a Google search was done for the exact phrase “stereochemistry tutorial”; 296 Web sites were found.14 However, none of these sites gave students the opportunity to choose their preferred method for determining the stereochemical relationships between molecules, nor did any allow for student interaction in order to make molecular comparisons. Several of the existing tutorials were geared specifically toward the university that published the site, decreasing the universal utility of those tutorials. Many of the other Web pages were simply lists of links to university sites or contained exact copies of the text and images from university sites. We have designed and generated a Web-based stereochemistry tutorial that allows each student to select a preferred method for determining the stereochemical relationships between molecules. This article describes development of the tutorial, which is available15 through the Chemical Education Digital Library;16 a second paper reports on student testing of the tutorial.17 Details of the rationale for our Web-based approach and of how the tutorial was designed and programmed are included in the Supporting Information.
Scheme 1. Outline of Format of the Instructional Sections of the Tutorial
tary examples are not required for student progress through the tutorial. This enables students to work through extra problems if they feel the need to strengthen an understanding of a concept or to avoid these extra problems if the students feel that they have a thorough comprehension of a particular topic. Finally, the students are able to take a short quiz, consisting of between 10 and 15 multiple choice questions in a subsection entitled Test Your Knowledge. The students are encouraged to complete this quiz without going back through the tutorial content. The questions cover information from the entire section and have a wide range of difficulty. The students select their answers using radio buttons, submit their choices, and are then taken to an answer page. The answer page indicates the number of questions the student answered correctly, repeats each question and the answer that the student chose, and finally gives the correct answer and an explanation of the correct answer for each question. This gives the students an opportunity to determine whether they successfully learned the presented concepts.
■
CONTENT AND PEDAGOGY The Introduction section of the tutorial briefly discusses the idea that molecules written two-dimensionally are really threedimensional. Furthermore, it is explained that altering a molecule’s three-dimensional character, even slightly, can drastically change a molecule’s physical and chemical properties. Here, students are given their first opportunity to view a molecule both in two dimensions, using carbon skeletons, and in three dimensions, using Jmol images that rotate around an axis to show the spatial orientation of the molecule (Figure 1). The students are also informed of the nonlinear nature of the tutorial, as well as the content of each of the other sections within the tutorial. The Definitions section of the tutorial is intended to familiarize students with the terminology that is frequently used when discussing stereochemistry. Vocabulary is introduced in order of increasing spatial complexity. Like all content-based sections of the tutorial, the Definitions section begins with an introductory page that has links to specific subtopics within the section. These links are another example of the availability of nonlinear navigation in this tutorial. The Three-Dimensional Representations section of the tutorial introduces students to the various ways in which a molecule can be drawn in two dimensions. Both acyclic (wedge−dash notation, Newman projections, sawhorse projections, and Fischer projections) and cyclic (wedge−dash
■
ORGANIZATION OF THE TUTORIAL The tutorial is organized to give students a strong foundation in core stereochemical concepts and then to apply that base knowledge to making stereochemical comparisons between molecules. There are six major sections: Introduction, Definitions, Three-Dimensional Representations, Assigning Priorities, Determining Stereochemical Relationships, and Question Sets. A sidebar with navigational links allows a student to select which section of the tutorial to work on and makes it easy for students to go back to previous sections to reinforce or revisit older content. Each instructional section of the tutorial follows the format in Scheme 1. First, a concept is introduced, typically with a definition or an explanation of purpose. Then, structural examples are provided to allow the student to “test” the given information. The tutorial is designed such that students can test a concept on their own, then go to the next page of the tutorial to check their answers. This design is intended to encourage students to create their own connections and logic regarding each topic. Once the students have completed the instructional pages on a specific concept, they have the option of working through additional examples on that topic. These supplemenB
dx.doi.org/10.1021/ed300744s | J. Chem. Educ. XXXX, XXX, XXX−XXX
Journal of Chemical Education
Article
are instructed to choose a method that they feel most comfortable with for acyclic (R and S, wedge−dash notation, Newman projections, sawhorse projections, and Fischer Projections) and for cyclic (R and S, wedge−dash notation, Haworth projections, and chair conformations) representations (Figure 2). On the basis of the method chosen, the students are then instructed on how to determine the stereochemical relationship between molecules. If the student chooses to make comparisons based on structures instead of R and S assignments, instruction is given on manipulating the other acyclic (or cyclic) representations into the representation of choice. It is important to note that regardless of which acyclic (or cyclic) representation is chosen for making stereochemical comparisons, the actual content presented to the students is identical. Therefore, although each section is tailored toward making stereochemical comparisons based on the student’s method of choice, the examples chosen and difficulty levels are consistent for all students. Additionally, the answer page for the Testing Your Knowledge questions within the Determining Stereochemical Relationships section of the tutorial is presented such that the explanation for the answer to each question is tailored to the student’s chosen method. Finally, the Question Sets section provides four additional quizzes, presented using the same format as previous Testing Your Knowledge sections. Each of the quizzes consists of 15 multiple-choice questions and covers information given throughout the entire Tutorial.
Figure 1. Partial screenshot showing Jmol images (top) and carbon skeletons (bottom) for molecular comparisons.
notation, Haworth projections, and chair conformations) are presented. As each two-dimensional representation is introduced, key concepts and three-dimensional information are included, as are connections to two-dimensional depictions that have been previously presented. The Assigning Priorities section of the tutorial first details the rules for assigning priorities, based on the Cahn−Ingold− Prelog rules, of different substituents on stereogenic carbons. These rules are then applied to determining the spatial orientation of double bonds and stereocenters. Finally, students are able to incorporate this spatial information into the names of molecules. The Determining Stereochemical Relationships section instructs students on how to compare molecules that are written using different structural representations. The students
■
CONCLUDING REMARKS This tutorial was evaluated in three student trials at the University of WisconsinMadison, and the results of these studies will be presented in a subsequent article.17 Results from student trials influenced subsequent development of the tutorial in order to make it as student-friendly as possible. After the completion of the third student trial, the finalized tutorial was moved to its current location,15 in the Chemical Education Digital Library (ChemEd DL).16 It is now a free, open-access tool for any student, teacher, or interested person to use. Within four months of being moved to this new Web address,
Figure 2. Partial screenshot showing the page for selecting a method for determining the stereochemical relationships between acyclic (left) and cyclic (right) molecules within the Determining Stereochemical Relationships section of the tutorial. The methods to select are shown enlarged in the corresponding inset. C
dx.doi.org/10.1021/ed300744s | J. Chem. Educ. XXXX, XXX, XXX−XXX
Journal of Chemical Education
Article
(14) Google search for “Stereochemistry Tutorial”. http://www. google.com/search?hl=en&lr=&as_qdr=all&q= %22Stereochemistry+Tutorial%22. June 28, 2007. (15) Stereochemistry Tutorial. http://www.chemeddl.org/ collections/stereochem/ (accessed Sep 2013). (16) Chemical Education Digital Library. http://www.chemeddl.org (accessed Sep 2013). (17) Burrmann, N. J.; Moore, J. W. Implementation and Student Testing of a Web-Based, Student-Centered Stereochemistry Tutorial, to be submitted for publication, 2013. (18) Google search for “Stereochemistry Tutorial”. http://www. google.com/search?hl=en&rls=com.microsoft%3Aen-us&q= Stereochemistry+Tutorial&aq=f&oq=&aqi=g2. November 18, 2009.
the tutorial was the second-most-popular search hit for “Stereochemistry Tutorial” on Google,18 which categorizes search popularity by the number of times a particular Web page is viewed. We hope that students and instructors in a variety of educational settings will use this tutorial to provide alternative methods for teaching stereochemistry and determining the stereochemical relationships between molecules.
■
ASSOCIATED CONTENT
S Supporting Information *
Development of the tutorial. This material is available via the Internet at http://pubs.acs.org.
■
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Present Address †
Math & Science Division, Heartland Community College, 1500 West Raab Road, Normal, Illinois 61761, United States. Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS
■
REFERENCES
Partial funding for the development of the tutorial was provided by the National Science Foundation, Grant DUE-0632303. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.
(1) Habraken, C. L. Integrating into Chemistry Teaching Today’s Students Visuospatial Talents and Skills, and the Teaching of Today’s Chemistry’s Graphical Language. J. Sci. Educ. Technol. 2004, 13, 89− 94. (2) Kozma, R. B.; Russell, J. Multimedia and Understanding: Expert and Novice Responses to Different Representations of Chemical Phenomena. J. Res. Sci. Teach. 1997, 34 (9), 949−968. (3) Wu, H.-K.; Shah, P. Exploring Visuospatial Thinking in Chemistry Learning. Sci. Educ. 2004, 88, 465−492. (4) Brun, Y.; Leblanc, P. The Flat and Direct Way to R and S Configurations. J. Chem. Educ. 1983, 60, 403−404. (5) Ayorinde, F. O. A New Gimmick for Assigning Absolute Configuration. J. Chem. Educ. 1983, 60, 928−929. (6) Mayer, R. E.; Sims, V. K. For Whom Is a Picture Worth a Thousand Words? Extensions of a Dual-Coding Theory of Multimedia Learning. J. Educ. Psychol. 1994, 86 (3), 389−401. (7) Eliel, E. L. The R/S Method: A Method for Assignment and Some Recent Modifications. J. Chem. Educ. 1985, 62, 223−224. (8) Barta, N. S.; Stille, J. R. Grasping the Concepts of Stereochemistry. J. Chem. Educ. 1994, 71, 20−23. (9) Gawley, R. E. Chirality Made Simple: A 1- and 2-Dimensional Introduction to Stereochemistry. J. Chem. Educ. 2005, 82, 1009−1012. (10) Lujan-Upton, H. Introducing Stereochemistry to Non-science Majors. J. Chem. Educ. 2001, 78, 475−477. (11) Ayorinde, F. O. Determination of Stereochemical Relationship. J. Chem. Educ. 1985, 62, 297−298. (12) Fox, S.; Madden, M. Internet Penetration and Impact; Pew Internet and American Life Project: Washington, DC, 2006. (13) Visual-Spatial Learning: Development of an Interactive WebBased Symmetry Tutorial. http://www.ccce.divched.org/ P4Fall2009ConfChem (accessed Sep 2013). D
dx.doi.org/10.1021/ed300744s | J. Chem. Educ. XXXX, XXX, XXX−XXX
