Representational competence (RC) is a set of skills to reflectively use a variety of representations to draw inferences, make predictions, and support claims. Despite the important role RC plays in student success in chemistry and the considerable number of investigations into student ability to reason with representations, little is known about instructors’ approaches toward developing student RC skills. This case study characterizes organic chemistry instructors’ intentions and practices toward cultivating their students’ RC. Three organic chemistry instructors participated in semi-structured interviews that explored their Pedagogical Content Knowledge (PCK) and goals for developing student RC. Interview data were triangulated with course artifacts data, including lecture slides and assessments. Several frameworks were used to deductively code the interviews and course artifacts: Kozma and Russell's RC, Geddis’ PCK, Ainsworth's functional taxonomy, and Johnstone's triplet. Through triangulation of different data sources and theories, we found differences in instructors’ PCK for teaching with representations, despite teaching the same course at the same institution. There were also differences in the alignment between each participant's instructional goals and what they enact when teaching and assessing representations. Specifically, two of the three instructors expressed explicit goals for developing student RC skills, which mostly aligned with the focus of their course artifacts. One participant, however, did not articulate any RC skills that they aim to teach and assess; yet, course artifacts revealed that they do use activities and assessment items that target some RC skills. This suggests that this instructor teaches and assesses RC skills without realizing it. Implications for instructors and education researchers are presented in light of these findings.

Polyethylene glycol (PEG) is a non-carcinogenic, water-soluble polymer of ethylene oxide that has found wide applicability in industry and medicine, and has been used to embed and section small animal and plant tissues. Here we investigate the use of PEG for the rapid embedding of larger plant tissues. Ovaries of Musa velutina, Heliconia psittacorum and eight other species were embedded with a mixture of PEG 1450 and PEG 4000. It was found that tissues up to 6.5 × 10 mm could easily be embedded and sectioned in PEG. Embedded tissues could be stored at room temperature for up to 5 days with no detrimental effects. Sections were easily cut at 8–15 μm on a rotary microtome. PEG embedding resulted in equal or better tissue differentiation, better retention of cell inclusions, and reduced shrinkage compared with paraffin embedding. The process was also faster, requiring only 3–6 h compared with the 2 days needed for paraffin embedding. PEG is a rapid-embedding medium suitable for use with even large plant tissues.