Transitions between representational levels: characterization of organic chemistry students’ mechanistic features when reasoning about laboratory work-up procedures

2020 ◽  
Vol 21 (1) ◽  
pp. 469-482 ◽  
Author(s):  
Liz Keiner ◽  
Nicole Graulich

Chemists refer to chemical phenomena on different representational levels—macroscopic, symbolic, and submicroscopic—which are directly related and connected to each other. Especially in the laboratory, students have to reason about various mechanistic features at the submicroscopic level and connect them in a meaningful way to make sense of the observable. There is plenty of evidence in chemistry education that students have difficulty connecting the different representational levels when thinking about chemical phenomena. However, current literature provides limited information about the mechanistic features that students activate when reasoning about phenomena and how they transition between the representational levels when in an organic chemistry laboratory. In this study, we performed in-depth analysis of how organic chemistry student teachers (N = 9) explained typical work-up procedures and characterized their activated mechanistic features and transitions between the different representational levels. Our analysis revealed that the students do not activate all features of a mechanism in the same way and construct various explanatory approaches. The findings emphasize the need to explicitly communicate how to connect the macroscopic and submicroscopic levels in a meaningful way in the laboratory. The implications of these findings for research, teaching, and learning to foster meaningful activation of mechanistic features are discussed.

2020 ◽  
Author(s):  
William J. Howitz ◽  
Kate J. McKnelly ◽  
Renee Link

<p>Large, multi-section laboratory courses are particularly challenging when managing grading with as many as 35 teaching assistants (TAs). Traditional grading systems using point-based rubrics lead to significant variations in how individual TAs grade, which necessitates the use of curving across laboratory sections. Final grade uncertainty perpetuates student anxieties and disincentivizes a collaborative learning environment, so we adopted an alternative grading system, called specifications grading. In this system each student knows exactly what level of proficiency they must demonstrate to earn their desired course grade. Higher grades require demonstrating mastery of skills and content at defined higher levels. Each students’ grade is solely dependent on the work they produce rather than the performance of other students. We piloted specifications grading in the smaller, third quarter course of the lower division organic chemistry laboratory series held during a summer term. Open-ended questions were chosen to gather student and TA perceptions of the new grading system. TAs felt that the new grading system reduced the weekly grading time because it was less ambiguous. Responses from students about the nature of the grading system were mixed. Their perceptions indicate that initial buy-in and multiple reminders about the bigger picture of the grading system will be essential to the success of this grading system on a larger scale.</p>


2008 ◽  
Vol 85 (12) ◽  
pp. 1644 ◽  
Author(s):  
Kate J. Graham ◽  
Brian J. Johnson ◽  
T. Nicholas Jones ◽  
Edward J. McIntee ◽  
Chris P. Schaller

2012 ◽  
Vol 89 (5) ◽  
pp. 685-686 ◽  
Author(s):  
Adam M. Kiefer ◽  
Kevin M. Bucholtz ◽  
David R. Goode ◽  
Jeffrey D. Hugdahl ◽  
Bridget G. Trogden

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