Evaluation of a Redesigned Chemistry Course Sequence for Undergraduate Life Science Majors

In response to both nationwide calls for reform and a perception that the existing chemistry curriculum was not meeting the needs of life science students, faculty in the department of chemistry at Purdue created a redesigned chemistry course sequence specifically aimed at preparing biology majors. The new sequence, called the 1-2-1 curriculum, spans four semesters of instruction, including one semester of general chemistry, two semesters of organic chemistry, and one semester of biochemistry. The 1-2-1 curriculum was implemented in the 2013-2014 academic year, and students appeared to be progressing through successfully. However, there was a need for a more systematic evaluation of the impact of the new curriculum on student learning and achievement. The goals of the 1-2-1 curriculum include preparing students for success in future chemistry courses, building students’ conceptual understanding of core chemistry topics relevant to biological systems, and having students apply their knowledge of chemistry to understanding biological systems at the molecular level. This study reports an evaluation of the 1-2-1 curriculum in three areas: students’ performance in subsequent courses, their retention of knowledge over time, and their transfer of chemistry knowledge to solve problems in biologically relevant contexts. Three cohorts of students were tracked through the 1-2-1 sequence and their performance was measured by course grades and exam scores. We found that students in the 1-2-1 curriculum performed better or equally well when compared to their peers who had taken traditional chemistry courses in both organic chemistry and biochemistry. To assess students’ retention of knowledge, a pre-test was administered at the beginning of biochemistry that included questions from the students’ general and organic chemistry final exams that covered topics relevant to biochemistry. Students’ responses to the pre-test were compared to their responses on final exams as a measure of retention. We found that students demonstrated higher retention for topics that were introduced in general chemistry and then revisited in different contexts in organic chemistry, including resonance, acid-base chemistry, intermolecular forces, and hybridization. Students demonstrated lower retention for topics that were introduced in general chemistry but not explicitly discussed in organic chemistry, including thermodynamics, kinetics, and buffers. Additionally, students generally demonstrated low retention when asked to draw mechanisms for reactions that they had been introduced to in organic chemistry. Transfer was assessed by asking students to propose mechanisms for reactions in both a traditional chemical context and a biochemical context. Students primarily constructed relations of similarity based on surface features of the starting materials, which often led them to propose incorrect mechanisms. Overall, these results demonstrate that the integration of topics throughout the 1-2-1 curriculum had a positive impact on students’ understanding and retention of core chemistry concepts, however, more work is needed to fully integrate other topic areas in the curriculum. Future changes to the curriculum are suggested, as well as broader implications for teaching, research, and curriculum development