by Terry O’Brien, Integrative Biology
Teaching Effectiveness Award Essay, 2000
During the 1990s, many science programs across the country replaced concepts-based learning with skills-based learning. Many teachers, however, have experienced difficulties in making the transition. Moreover, they have noted that some students do not seem to benefit from the skills-based learning. One reason for this is that in many skills-based courses, students are not given a conceptual framework in which they can situate the skills that the course emphasizes. Instead, many instructors are simply asking their students to practice the skills, without giving them the conceptual structures that give those skills meaning. In my experience, no matter how much students practice whatever skills, few are able to develop a clear conceptual matrix for those skills without significant guidance from the instructor. A direct approach to this problem means that the instructor first provides students with the scaffolding of concepts for each skill. In this essay, I describe an exercise that can be used to develop a framework for students to evaluate what they observe in their laboratory exercises.
During a course, I dedicate portions of several class meetings to the development of a conceptual framework for evaluating explanations of observations. A week in advance of each session, I distribute two questions that we will discuss in class the following week. In the next class meeting I divide students into small groups and brainstorm answers for about fifteen minutes. For the next ten minutes, I moderate as each group shares their ideas with the entire class and I record the consensus position derived from the views the groups have presented. As soon as is practical, I distribute a statement of this consensus position. In this way, in the minds of the students, the work of the session is extended over two or three weeks even though the session itself lasts for only part of a class meeting.
In each session, I pose two questions for discussion that address either one key issue that helps the students work towards the larger goal of creating a conceptual framework for explanation of observations. I don’t reveal the goal to the students before they brainstorm because focusing on the goal itself may short-circuit their thinking in the crucial early stages of the process. The goals are arranged so that each session’s work builds on the work of the previous session.
Goal of the first session: identify different types of explanation. Questions:
- Can two or more explanations for an observation be correct? Why? Provide examples.
- What are the differences between an explanation, a speculation, a hypothesis and a theory?
Goal of second session: define how the quality of an explanation is assessed. Questions:
- What is a satisfactory explanation in science? Describe its essential traits.
- How can you know if an explanation is correct?
Goal of third session: consider sources of errors in explanations. Questions:
- What general problems lead us to wrong explanations? Provide examples.
- Must the assumptions of an explanation be true for the explanation to be correct? Why? Provide examples from this course.
Goal of final session: consider the continuum of the quality of explanations. Questions:
- Is there any worth in an unsatisfactory explanation? Explain.
- Why are some explanations easier to evaluate than others? Explain, using examples from this course.
It is important that the sessions are evenly distributed throughout the semester, rather than packed into a three- or four-week section of the course. Careful distribution of the sessions allows students to develop their conceptual skills in parallel with the development of the course. Most science courses progress toward a synthesis of concepts so spacing the sessions allows students to tackle critical thinking in a variety of conceptual landscapes. Spreading the sessions throughout the semester is also beneficial because students have a better long-term memory for what they have learned about evaluating explanations.
Is this strategy effective in enhancing students’ evaluations of explanations? The improvement in the quality of written work as well as students’ comments about the sessions suggest that this is a productive strategy for teaching skills and concepts. The most obvious developments in their writing are that students begin to show that they know when to question explanations and that they also can suggest how to evaluate them. It also frequently happens that a student will say to me “I never really thought about how to evaluate explanations” or “The truth in explanations is a lot more complex than I thought.”