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In the past few decades, there has been a large push for increasing scientific literacy (AAAS, 1989; AAAS, 1993; Achieve, 2013; NRC, 1996; NRC, 2012), especially in areas that are rapidly advancing, like molecular genetics. Much research has been done on student understandings of molecular genetics and the consensus is that the concepts are difficult both to learn and teach (Fisher, 1992; Horwitz, 1996; Kindfield, 1992; Lewis & Kattmann, 2004; Marbach-Ad & Stavy, 2000; Stewart et al., 2005; Venville & Treagust, 1998; etc.). Two learning progressions in molecular genetics have been produced (Duncan et al., 2009; Roseman et al. 2006), but both progressions are hypothetical as neither have been fully empirically tested. This study filled several gaps in molecular genetics research such as empirically testing the molecular genetics learning progressions in three 10th grade classroom contexts in different schools, determining the impact of curricular intervention units targeted to certain constructs of one of the progressions, and revising and refining the progressions based on empirical data.The data collected show that 10th grade students fall on the extremely low levels of the progression prior to instruction and progress through the defined levels of the Duncan et al. (2009) progression for each construct. Students hold several lower and intermediate ideas that were added to the progression as new levels in each construct. It was difficult to quantify the impact of the intervention units with quantitative data, but qualitative data suggest that certain ideas emphasized in the units such as a gene, protein, cell, trait scaffold and several specific examples of protein structures and functions were useful for students to understand ideas in molecular genetics. Additionally, two of the constructs of the Duncan et al. (2009) progression were divided into two new constructs each, and an entirely new construct was added to combine the Duncan et al. (2009) and Roseman et al. (2006) progressions. This is the first study to empirically test, revise, and refine all constructs of the Duncan et al. (2009) molecular genetics learning progression and to combine the Duncan and Roseman progressions into a single learning progression. |
