Teach the Earth > Rates and Time > Workshop 2012 > Participants and their Contributions > Sarah Gerken

Student Misconceptions about Oceans and Evolution

Sarah Gerken, Department of Biological Sciences and Liberal Studies, University of Alaska, Anchorage

The University of Alaska Anchorage has about 16,000 students, although only 40% are full time students. The student body is a mix of traditional and non-traditional students, coming from a diversity of backgrounds including Alaska Native cultures, remote village and small communities as well as the municipality of Anchorage. Thus, classes tend to be composed of a very diverse group of students with a broad range in preparation for college. The main lower division courses that I teach are a course called Life on Earth for elementary education majors, and Fundamentals of Oceanography, an introductory, general education for non-majors.

Problems in student understanding encountered in Fundamentals of Oceanography include difficulty in comprehending the age of the earth and the relative age of the current configuration of the ocean basins, and the origin and destruction of oceanic crust. When given choices in exam questions, the ones that pertain to ocean basin formation and change are generally avoided, and these are some of the questions with the poorest student performance when no choice is allowed. In Life on Earth, students have serious misconceptions about the relative ages of various types of organisms, such that they regularly suggest that land plants are older than animals. Order of appearance is fundamental to understanding the evolutionary relationships among organisms. For example, this misconception that land plants are older than animals then suggests that animal-like eukaryotic cells evolved from plant-like eukaryotic cells.


In Oceanography, the history of the earth is presented in a linear framework, and it is clear from the student misconceptions that this is not particularly effective. As the class is focused on the oceans, there isn't much time to address the history of the planet and plate tectonics, but the current approach does not seem to get the concepts across to the majority of students. In Life on Earth, time is also presented in a linear fashion, in the form of a timeline with the origins of various important groups of organisms on the time line, to try to emphasize the relative ages of various groups, but this seems to be ineffective as the misconception persists. Part of the confusion seems to stem, anecdotally, from student concepts of changes in the earth's atmosphere due to biological processes (prokaryotic photosynthesis) and the fact that land plants are photosynthesizers. While it is true that the process of photosynthesis predates eukaryotic animal origin, the converse is not true, that all photosynthesizers are older than animals. One of the things I hope to gain from participation in this workshop is efficient ways of guiding students away from their misconceptions about time and timing, to enhance their understanding of the oceans and evolutionary relationships.
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