This chapter presents conclusions based on the results described in this dissertation and is broken down into three sections. The first section focuses on conclusions related to the integration of scale themed instruction into general chemistry I and II courses. The second section focuses on the limitations of the research presented and the third section focuses on the implications these results have for instruction in both the domain of chemistry and the discipline of science. The final section briefly describes the on-going continuation of this work and possible future directions of this project.
5.1 Conclusions
Integration of explicit scale-themed instruction in an undergraduate general chemistry course has been accomplished through rigorous control/treatment cohort testing by incorporating
supplemental instruction and adapting laboratory experiments and lecture instructional materials. In general chemistry I, several important results demonstrate that explicit incorporation of this theme into instruction directly led to increased demonstrated proficiency by students on chemistry assessments. This proficiency was measured by positive changes in student
performance on pre-laboratory quizzes, a laboratory survey, and final exams. Most importantly, trends in the observed positive changes were consistent with expected trends based on control testing and combined treatment effects. Notably, residual averages for the combined treatments of supplemental instruction, laboratory experiments, and active learning lecture activities over
85
three repeated semesters of testing showed consistency in improving student final exam scores 4.9%-6.7% on the ACS Exams Paired Questions Exam and 4.2%-5.1% on the ACS Exams First Term Conceptual Exam.
5.2 Limitations
Limitations to this work center around the many variables that exist when instituting curricular change such as the instructor of record and teaching assistant turn over. During the time period in which this data was collected it is possibly that any one of three rotating instructors of record taught general chemistry I, general chemistry II, or both courses during a single semester. While the rotation of these instructors provides validity to the observed consistency in results, it is unlikely that any one instructor was able to completely separate themselves from incorporating concepts of scale during lecture control semesters once implemented. In a similar vein, over the course of the 10 semesters in which this research was conducted, countless teaching assistants were responsible for overseeing student completion of the scale themed laboratory experiments and completion of the active learning lecture assignments in discussion. Teaching assistants in these positions were often unaware of the great deal of influence their perceptions of these research objectives had over student perceptions and it is possible that some teaching assistants’ experiences influenced the experience of the student.
86
5.3 Implications for teaching
While instructional standards such as the AAAS Benchmarks for Science Literacy and more recently, the Next Generation Science Standards provide a strong argument for the
incorporation of themes into instruction, at this time only 18 states plus the District of Columbia have adopted the standards. Furthermore, as the standards only specify what a student needs to know or do to demonstrate proficiency little is known as to the extent by which the standards in those states are incorporated into teaching. Compounding factors, such as incorporating of a single cross-cutting concept which draws together scale, proportion, and quantity greatly
diminished the extent by which scale is conceptualized as distinctly different from proportion or quantity. The implication of this being that upon assessment, an instructor might feel as though they adequately address the cross-cutting concept in their classroom while actually only
addressing two thirds of the standard.
As noted throughout the body of this dissertation, all of the instructional materials developed as a part of this work are available to any instructor who may wish to integrate them into their curriculum. While it is the goal of the research that an instructor would be able to drop these materials into their chemistry curriculum and observe positive changes in student
performance, more importantly, what this research does is provide an instructional guide for any instructor in science who wishes to incorporate themes into instruction. Although the efficacy of scale-themed instruction in increasing student performance in chemistry has been demonstrated in this work, it is possible that incorporation of other themes, possibly in conjunction with scale, could further improve science literacy.
87
5.4 Future directions
As found in this work, the role understanding scale plays in understanding chemistry and the effectiveness of scale-themed instruction in general chemistry II is less well understood than in general chemistry I. A longitudinal study into the conceptions of scale held by students at the start of general chemistry II or for those continuing into organic chemistry courses could provide insight into instructional targets related to helping students further develop skills related to scale. As evidenced in the work of Jones and Taylor, scale is a theme that pervades any science course, not just chemistry. Knowing the degree to which scale conception impacts student performance in chemistry, it is logical to assume that undergraduate students in other science disciplines demonstrate the same deficiencies. As many of the themes of scale that are present in chemistry are also mirrored in biology courses, most noticeably the connection between the macroscopic and microscopic realms, the extension of this work into a biology course is currently underway.
88