Instruments
The instruments used in this study were developed by the author. The pretest and posttest were designed to measure student understanding of series and parallel dc circuits and hence belonged to the cognitive domain. Bloom's taxonomy (1956) was used as a guide to develop a blueprint for the pretest and the posttest. On analyzing the pilot study data, the Cronbach Reliability Coefficients for the pretest and the posttest were found to be 0.91 and 0.87 respectively.
The posttest was a paper- and- pencil test consisting of 15 "drill- and- practice" items and 15 "critical- thinking" items. The items that belonged to the "knowledge," "comprehension," and "application" classifications of Bloom's Taxonomy were categorized as "drill- and- practice" items. These items pertained to units and symbols of electrical quantities, total resistance in series and parallel, and simple applications of Ohm's Law. The items that belonged to "synthesis," "analysis," and "evaluation" classifications of Bloom's Taxonomy were categorized as "critical- thinking" items. These items required students to clarify information, combine the component parts into a coherent whole, and then judge the solution against the laws of electric circuits. The pretest consisted of 12 items, two items belonging to each classification of Bloom's Taxonomy.