The effects of using dichotomous keys with analogies on college students' understanding of biology concepts
Tillman, Robin Francis
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My introductory biology students are expected to acquire an extensive vocabulary and I have noticed that they often struggle to learn and make connections between the many Greek and Latin derived terms. This study investigated the effects of dichotomous keys with analogies on college students' understanding of concepts. Twenty adult students enrolled in one section of my Grade 12 equivalent biology course participated. A combination of quantitative and qualitative data collection tools were used to evaluate my intervention's impacts on understanding, long-term memory, and higher-order thinking skills. Data from the three treatment units were compared to one nontreatment unit during which only existing teaching methods were employed. Paired two-tailed t-tests were used to quantify any differences observed between the preunit, postunit, and delayed unit assessment scores. Student-generated works, and interview data obtained from low-, middle-, and high-achieving students, were compared to allow for triangulation of the data. Other forms of data collection were used to determine the effects of dichotomous keys with analogies on biology students' attitudes and motivation. Students' written comments on pretreatment and posttreatment attitude scales were compared to identify trends and outliers, while responses to Yes/No questions were quantified using chi-square analyses. In addition, teacher journaling and classroom observations by a peer observer were employed. The effects on my own teaching, time management, and attitude were assessed through the use of teacher attitude scales, journaling, and peer observations. The data indicate no significant improvement in students' overall conceptual understanding and higher-order thinking skills following the treatment period, but significant benefits were observed with respect to concept retention. Both lower-order thinking skills, and student and teacher attitudes and motivation, yielded mixed results. One group of students thrived during the prolonged use of dichotomous keys, while the other group became frustrated with, and disengaged from, its highly structured format.