Stirring the Biology Teaching Pot with Discrepant Events

Abstract

THE biology class was in the process of finishing up a genetics laboratory exercise. Students had planted and germinated corn seeds that exhibited two phenotypes-one with chlorophyll and the other without chlorophyll (albino). The teacher, hoping to move on to a discussion of seeds, asked the students how the albino plants were able to grow even though they possessed no chlorophyll. During the ensuing silence of thought, Frank's hand shot up and without being called upon, he said, My uncle is an agronomist, and he told me that when corn is planted in the dark it grows faster than in light. Could that be true? Mary, who had until then been staring out of the window, turned around and commented that Frank's uncle was crazy and did not know what he was talking about. This was not the hoped for response; however, the teacher knew that Frank's uncle was correct, and that this would serve as a place to begin the discussion. The teacher had two options at this point: explain the reason or encourage an open-ended discussion by saying, I know that it doesn't seem possible, but if you consider all the facts, you might agree with the answer given by Frank's uncle. The teacher wisely chose the second option. For the next 20 minutes, the teacher focused student discussion on the details of plant growth, then asked students what stimulated plants to grow. Water, food, sunlight and minerals were all mentioned as sources. The teacher, in probing these responses, asked specifically which were essential for corn seeds to grow in the dark. The students were not sure and requested additional information about plant growth; they had a desire to know. The students, by themselves, still could not resolve the problem. Even with their insistence for closure, the teacher decided to perpetuate the activity. The students were then guided to design an experiment to test the hypothesis that corn seedlings grow faster in the dark. With as little input as possible from the teacher, the students were given corn seeds and asked to proceed with their experiment. Once they thought they had a good design with sufficient controls for relevant variables, the students assembled the necessary equipment to plant the seeds in two flower pots labeled A and B. Flower pot A was kept in a lighted area and flower pot B was placed in darkness. Twice daily they observed and measured the seeds' rate of growth (any combination of time chosen was acceptable) until several days past the successful germination of all the viable seeds. (It was then observationally concluded by the students that the corn seeds in flower pot B had grown taller than the ones in A.) The event that took place in this hypothetical biology classroom is a good example of how one might motivate interest and provoke active student participation. This would then challenge their basic conceptual framework of events in the world around them. When the student predictably admits, It can't happen that way; that just isn't so, the teacher has created an opportunity for discovery through logical inquiry and/or application of scientific concepts and principles. This is a teaching maneuver adopted to elicit appropriate student behaviors that promote the achievement of desired educational objectives. Indeed,