COMMENTARY pubs.acs.org/jchemeduc
Using Topic Order To Reinforce Student Algebra Skills in a Community College Introductory Chemistry Course Alan W. Blakely* University of Kansas School of Medicine—Wichita, Wichita, Kansas 67214, United States ABSTRACT: This article describes the impact of starting with gases in an introductory chemistry course at a community college. Students in the author’s class frequently are very weak in algebra skills, and this has a cumulative impact over time that culminates in student struggles when moles and reaction stoichiometry are discussed. The rationale behind starting with gases was that the topic has a relatively small content load while giving students the opportunity to manipulate and apply algebraic equations. The author observed improved student performance, particularly when discussing moles and stoichiometry. KEYWORDS: First-Year Undergraduate/General, Curriculum, Analogies/Transfer
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he topic sequence in introductory and general chemistry textbooks is quite consistent. They typically begin with a discussion of units, measurement, and the metric system; discuss states of matter and energy; move on to atomic theory; and so on (cf. refs 1 or 2). This general topic sequence has survived for many years, and it makes sense from a content development perspective; it builds chemistry from its most basic elements and develops more complex material as it proceeds. Only once in 20 years of teaching from introductory and general chemistry texts have I used a book that actively encouraged an instructor to deviate from this sequence.3 However, for many students, the traditional topic sequence may not be an ideal order in which to present the topics, and there have been calls for reform of the general chemistry and, by analogy, the introductory chemistry curricula. For example, Hawkes4 called for a revolution in introductory (by which he means general) chemistry topic content, advocating for a set of topics much more relevant to today’s practicing scientists and engineers. Half a decade later, Cooper5 reiterated the need for change and expressed similar reasons and obstacles to success. Where Hawkes and Cooper proposed change in the abstract without committing to particular curricula, Yoblinski6 describes a general chemistry curriculum used at Appalachian State University that tries to order topics more logically than in conventional chemistry textbooks. This paper describes another attempt at reordering the topic sequence in an introductory chemistry course in order to facilitate student success.
and have tried lecture review and worksheet activities in lab, but this has failed to ameliorate the problem. Students still flounder when we discuss stoichiometry, reaction yield, and so forth, and performance on the department final exam has been consistently lackluster. For the spring semester of 2010, I attempted to put to use some ideas regarding horizontal and vertical transfer of knowledge.7 Here, horizontal transfer refers to the assignment of new information into an existing structure or scheme; vertical transfer is the association between resources to create a new structure or scheme. In contemporary constructivist learning theory, horizontal transfer is a form of assimilation, and vertical transfer is a form of accommodation.8 Horizontal transfer is linked to efficiency of knowledge use, while vertical transfer is linked to innovative use of the knowledge. In the knowledge construction process, a balance must be achieved between these two learning modes; too heavy an emphasis on horizontal transfer leads to student boredom, and too much emphasis on vertical transfer leads to student frustration. This can be expressed in terms of Vygotsky’s zone of proximal development.9 If a teacher relies too much on horizontal transfer, the lesson will be within a student’s level of actual development and will not contribute to further growth. However, if a teacher relies too much on vertical transfer then a given student may be operating entirely within his or her level of potential development; as with too much reliance on horizontal transfer, this will not contribute to further growth; however, instead of failing because it is not stretching the student’s capacity, the failure will now be because the student has not reached the level of development that will allow mastery of the new material independently. By balancing the two learning modes, a teacher can help a student operate within his or her zone of proximal development, the range of material that a student can master with teacher guidance. My insight at the time I heard the paper presented was that we tend to ask our introductory students to do the harder of the two tasks. One of the goals of many introductory science classes is to try to get students to see how the science in the discipline can be
’ UNDERSTANDING THE NATURE OF THE PROBLEM IN MY COURSE I currently teach introductory chemistry as an adjunct professor at a community college in the Midwest. This course targets students who have not taken high school chemistry or are otherwise unready for, or may not need, general chemistry; when finished with the course, students should be prepared for general chemistry. I routinely teach in the 5:30 8:30 time slot with lecture taking approximately the first half of the period and lab the second. Whether it is due to the time slot, the student grapevine that gets students to select me as the professor, or some other reason, the students who enroll in my class have particularly weak algebra skills. I have struggled with this for several semesters Copyright r 2011 American Chemical Society and Division of Chemical Education, Inc.
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Journal of Chemical Education applied “in the real world” and to give the students a grounding in the nature of science and its particular, systematic approach to problem solving. Consequently, we may skimp on the drill and practice focusing on solidifying the computational skills that we know our science majors will need in order to continue in the subject. My insight in 2010 was that I had fallen into precisely this trap in my own classroom. I consistently saw a pattern in student difficulties in my class. The early going would be relatively smooth until we reached the part of the course in which we cover reactions and stoichiometry. In our text, moles are introduced first, followed by writing and balancing reactions, and the sequence finishes with stoichiometric calculations. At this point, students hit a wall. Moles seem to be okay, though student development is quite labile; what made sense yesterday becomes opaque by the day after tomorrow. Writing and balancing reactions also seems to be something that the students are comfortable with, but when the two ideas are put together in the stoichiometry chapter, the students’ fragile knowledge structures come tumbling down. No matter how I have reorganized material, changed presentations, and changed scaffolding, students struggle mightily and apparently out of proportion to the difficulty of the material.
COMMENTARY
how well students do on topics on the final exam every semester, and this group of students did better in most topic areas, and specifically in moles and stoichiometry. In addition to offering a potential solution for other chemistry instructors facing similar issues, the general take-home lesson is that every so often we need to re-examine our assumptions and conventions about our courses and our teaching. Some things we must keep in order to maintain the integrity of our disciplines, yet our students, their needs, and society itself are constantly changing, and we need to be sure that we are presenting material in the most effective ways possible. As the masters of our disciplines, we need to find ways to mold our teaching to our students rather than forcing them to fit into our preconceived models of science students.
’ AUTHOR INFORMATION Corresponding Author
*E-mail:
[email protected].
’ REFERENCES (1) Tro, N. J. Introductory Chemistry Essentials, 3rd ed.; Prentice Hall: Upper Saddle River, NJ, 2008. (2) Zumdahl, S. S.; Zumdahl, S. A. Chemistry, 8th ed.; Books/Cole: New York, 2010. (3) Peters, E. I.; Cracolice, M. S. Introductory Chemistry: Flextext, 1st ed.; Saunders College Publishing: Fort Worth, TX, 1998. (4) Hawkes, S. J. Introductory Chemistry Needs a Revolution. J. Chem. Educ. 2005, 82, 1615–1616. (5) Cooper, M. The Case for Reform of the Undergraduate General Chemistry Curriculum. J. Chem. Educ. 2010, 87, 231–232. (6) Yoblinski, B. J. Sequencing General Chemistry: A New, More Logical Approach. J. Coll. Sci. Teach. 2003, 32, 382–387. (7) Rebello, N. S. Consolidating Traditional and Contemporary Perspectives of Transfer of Learning: A Framework and Implications. In Proceedings of the NARST 2007 Annual Conference, New Orleans, LA, 2007. (8) Matthews, M. R. Constructivism in Science Education: A Philosophical Examination; Kluwer Academic Publishers: Dordrecht, 1998; p 234. (9) Vygotsky, L. S. Mind in Society; Harvard University Press: Cambridge, 1978; p 159.
’ CHANGING THE TOPIC ORDER TO CHANGE OUTCOMES My working hypothesis was that the conceptual layering combined with the heavy reliance on algebraic skills was leading to cognitive overload for the students. To combat this, I moved my initial coverage of gases (Chapter 11 in our text) to the very beginning of the course. My rationale for this is that students generally have a good intuitive grasp of the basic gas laws, so I can use this to give them more practice manipulating algebraic equations and variables and formalizing their extant content knowledge rather than adding new material. At this point, I just focused on Boyle’s law, Charles’ law, Gay-Lussac’s law, and the combined gas law. We had to discuss temperature scales along the way, but that seemed a small additional thing to add at this stage. I put off the discussion of Avogadro’s law and the ideal gas law until after we had begun the discussion of moles. This was a distinctive success in my class. Qualitatively, early in the semester it seemed to be the missing piece of scaffolding to give my students the mathematical foundation they needed; they seemed more comfortable combining the conceptual and computational material as we got deeper into the semester. This was a good balance of horizontal and vertical transfer for this group of students. They had the chance to practice basic mathematics skills without falling into boredom while still working on applying new knowledge without crossing the frustration threshold. The questions asked by the class were also of a higher level, focusing more on applying equations over how to solve for x in an equation. Additionally, starting with gases gave me a very nice lead-in to a discussion on the particulate model of matter. The acid test, of course, was whether it made students more successful at grappling with moles and stoichiometry. The qualitative improvements I saw earlier also held true in our discussions of these two difficult topics. In addition to “seeming” to do better, they also scored better than previous classes on the department final exam. Average scores went up by six points out of 100, which is statistically significant (p < 0.01), though, because this was not a controlled study, it would require further examination before it becomes truly meaningful. I keep track of 859
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