Development of Cognitive Skills Using an Inquiry-Based Approach to Teaching Disease Cycles

Sharon Yelton and Paul Vincelli
Department of Plant Pathology
University of Kentucky
Lexington, Kentucky
 USA

Introduction

Implementation of teaching methods that actively engage students in the learning process can be beneficial to student learning (2, 3, 4).  In our introductory plant pathology class at the University of Kentucky, we have implemented an alternative, inquiry-based teaching method (5).  We believe that our approach fosters the development of important cognitive skills by increasing each student’s responsibility for his/her learning. Recognition of these skills is in accordance with the cognitive domain of learning described by Benjamin Bloom et al. (1) and defined as six skill levels, listed here from simplest to most complex:  Knowledge, Comprehension, Application, Analysis, Synthesis, and Evaluation (1).

Pre-Class Preparation of Disease Cycles

Early in the semester, students become familiar with the components of the disease triangle and are given a list of symptom terminology, a working definition of each of the nine components of the disease cycle, and a list of questions to answer/consider for each disease (5).  It is the responsibility of each student to complete the assigned reading and prepare a disease cycle prior to attending class, where it will be discussed.  This pre-class work, combined with the in-class discussion, challenges all cognitive skill levels.  

In their pre-class preparation, students are asked to identify the name of the pathogen and to describe the host range.  Since these are facts directly stated in the reading, Knowledge is the cognitive skill being challenged.  Furthermore, questions specific to each stage of the disease cycle require Knowledge or Comprehension (e.g., “How does the inoculum disperse?” or  “List key symptoms on all plant parts affected”).  However, complete preparation of a disease cycle requires the higher cognitive skills of Analysis and Synthesis.  Students must pull apart the reading material, identify important events, and discover the relationships between these events, thereby providing a challenge at the level of Analysis.  The skill of Synthesis is developed in that they must then reorganize and arrange these events to produce a disease cycle that is precise, accurate, and recapitulates the model used in class (5).  Therefore, the student must first comprehend the reading material, then analyze, and from it synthesize an integrated whole from pieces of information.

The cognitive skill of Application can also be used to construct a disease cycle that might be especially challenging. As the course progresses and knowledge of pathogens and disease cycles becomes greater, so does the ability of the student to make use what they have previously learned.   For example, a student may be able to apply what was learned about Phytophthora spp. in order to develop and organize disease cycles of other Oomycetes such as Plasmopara viticola that might seem especially difficult.

The last task students must do when preparing a disease cycle is to think about factors that affect the disease triangle.  For example, a student may ask him/herself how an environmental factor such as an unseasonably hot and humid summer may affect production and dispersal of inoculum that causes Pythium blight.   The first cognitive skill challenged is Comprehension since the student must understand the disease cycle in order to extrapolate information and conceptualize the disease triangle.  The skill of Analysis is again being challenged because students must examine how an environmental factor relates to the disease cycle.

In-Class Discussion of Disease Cycles

Many of the higher cognitive skills are challenged in the pre-class preparation, but the classroom environment provides clarification, explanation, and further development of students’ cognitive skills.  During discussion of the disease cycle assigned for that class period, an inquiry-based approach challenges these cognitive skills and fosters a more complete understanding of the disease.  

For example, while discussing Phytophthora disease cycles, students may be asked, “What type of spores are the primary inoculum?”  To answer this question requires Comprehension of the disease cycle, but because it requires the students to differentiate the types of spores produced by the pathogen and consider their respective roles in the disease cycle, Analysis is also challenged.  When discussing the Agrobacterium tumefaciens disease cycle in another class, students may be asked, “Which pathogen structure is colonizing the plant?”  This question requires the use of cognitive skills beyond simple recall.  Specifically, Application of knowledge obtained from previous study of other bacterial diseases as well as Comprehension of the disease cycle would help the student answer this question.

At the end of the class period, students form small groups to discuss management practices.  This is followed by generation of a master list from volunteer contributions from the entire class.  Deciding which control measures would be appropriate requires students to consider everything they have just learned regarding the specific disease cycle such as how the pathogen infects the host, factors that favor disease, etc.   Judging which management practices are not only possible, but economical and effective, challenges the cognitive skill of Evaluation.

Conclusions

Our inquiry-based method for teaching disease cycles in an introductory plant pathology classroom provides an excellent opportunity to challenge and develop students’ cognitive skills.  Although a nontraditional method, an inquiry-based approach is also utilized to introduce students to fundamental principles and concepts of our discipline.  Transferring more of the responsibility of learning to the student via pre-class preparation and using question-and-answer-based class discussions of the disease cycles are aspects of this approach that challenge and enhance all cognitive skill levels.

References

1. Bloom, B. S., ed.  1956.  Taxonomy of Educational Objectives:  The Classification of Educational Goals:  Handbook I, Cognitive Domain.  Longmans, Green, NY.
2. Chew, F. S.  1992.  Peer Interaction Boosts Science Learning.  Pages 156-165 in Thomas Warren, ed.  A View From the Academy, Liberal Arts Professors on Excellent Teaching.  University Press of America, Lanham, MD.
3. Mazur, E.  1997.  Peer Instruction, A Users Manual.  Prentice Hall, Upper Saddle River, NJ.
4. Uno, G. E.  1997.  Learning about Learning Through Teaching About Inquiry.  Pages 189-200 in Ann P. McNeal and Charlene D’Avanzo, eds.  Student-Active Science, Models of Innovation in College Science Teaching.  Harcourt Brace and Co., Ft. Worth, TX.
5. Vincelli, Paul.  2005.  An Inquiry-Based Approach to Teaching Disease Cycles.  The Plant Health Instructor DOI: 10.1094/PHI-T-2005-0222-01.

Date: 15th May, 2006 email: syelt2@uky.edu

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