Several researchers have documented students' misconceptions in electrochemistry. One reason for the interest in studying electrochemistry is that surveys of students and teachers suggest that students find this topic difficult and research confirms that students' beliefs about problem complexity affect their performance and learning. Several articles have promoted pedagogical suggestions or opinions about more effective mehods of teaching electrochemistry; but few, if any, of these have actually been tested.
This study replicates, with additions, research done by Garnett and Treagust. Garnett and Treagust's interview questions for galvanic and electrolytic cells were used with modifications; concentration cell questions were asked in a similar manner. These questions were administered to 16 introductory college chemistry students after electrochemistry instruction. Student misconceptions most commonly encountered included notions that electrons flow through the salt bridge and electrolyte solutions to complete the circuit, plus and minus signs assigned to the electrodes represent net electronic charges, and water is unreactive in the electrolysis of aqueous solutions. New misconceptions identified included notions that half-cell potentials are absolute and can be used to predict the spontaneity of individual halfcells, and electrochemical cell potentials are independent of ion concentrations. Most students demonstrating misconceptions were still able to calculate cell potentials correctly, which is consistent with research suggesting that students capable of solving quantitative examination problems often lack an understanding of the underlying concepts. Probable origins of these student misconceptions were attributed to students being unaware of the relative nature of electrochemical potentials and chemistry textbooks making misleading and incorrect statements. A minor technical flaw in the Garnett and Treagust study is also addressed.
This analysis was inspired by a student comment made during a clinical interview in electrochemistry (1). The student was asked to identify the anode and cathode of an electrochemical cell consisting of a Ni/Ni 2+ half-cell on the left and a Ag/Ag + half-cell on the right. STUDENT: I was just told that this would be the anode on the left [Ni] and the cathode on the right [Ag]. INTERVIEWER: But what if we gave you a diagram like this? [Reversing the half-cells.]STUDENT: Well then, it [nickel] would be reducing-the cathode, right. That's just so far how the book has shown it to me and the way on the board it's been shown.
The Science Writing Heuristic (SWH)
laboratory instruction approach
has been used successfully over a decade to engage students in laboratory
activities. SWH-based instruction emphasizes knowledge construction
through individual writing and reflection, and collaborative learning
as a group. In the SWH approach, writing is a core component of learning.
Previous studies on the SWH approach have reported effective implementation
of the SWH approach leads to an improvement in overall student academic
performance and content knowledge. Using a rubric developed by Maria
Oliver-Hoyo, we compared the critical thinking (CT) skills of students
across three groups, based on their written laboratory reports for
various traits of CT, and the cognitive skills embedded in the rubric.
Participants in this study were first-year general chemistry students
who received traditional laboratory instruction, first-year general
chemistry students who were instructed using the SWH approach, and
fourth-year chemistry students who received traditional laboratory
instruction. First-year students and fourth-year chemistry students
who received traditional laboratory instruction scored statistically
significantly lower on various CT traits, suggesting the SWH-based
laboratory instruction is valuable in promoting CT thinking skills
of students.
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