Edpsy 399 OL - Spring 2000
Tom Anderson, Instructor
Forum 11 - Lesson 11
Date: Sat April 21 2001
Subject: Lesson 11 q5
Metaphors in Teaching
A water hose and the accompanying system of taps, flow meters and pumps are often used to explain electricity, especially an electric circuit. Using this instructional analogy or another from your field of expertise, explain how the use of analogies can be helpful and detrimental to students' understanding of the primary concept(s). For example, in the above analogy, an electrical circuit is the primary concept.
Ideally, students progress from concrete to abstract thinking and begin to develop mental models of science concepts as they advance in school. In order for students to begin to develop mental models in science, teachers often find it useful or necessary to use models and analogies. The teacher uses physical models and analogies to show the students simplified, comprehensible descriptions of concepts.
Glynn, (1998) found that in science texts, analogies are used to transfer ideas from a familiar concept to an unfamiliar one. The familiar concept is frequently referred to as the analog, while the unfamiliar one is known as the target. If the analog possesses features that are also common to the target, an analogy can be drawn between them.
Analogies in text can help to build meaningful relations between what students already know and what they are setting out to learn (Glynn & Takahashi, 1998). The activity of building relations between present knowledge and new knowledge is important in the students' learning process. Familiar analogies can serve as early mental models in which students can form limited but meaningful understanding of more complex concepts. As the students progress cognitively and learn more science, they will hopefully evolve beyond these simple analogies and adopt a more sophisticated and powerful explanatory model.
Glynn (1998) goes on to discuss the important role analogies have in scientific discovery. For example, Joseph Priestley was thinking analogically when he proposed a law of electrical force. Priestley was familiar with Newton's Law of Universal Gravitation, which holds that the gravitational force between any two bodies varies inversely as the square of the distance between them. Priestley speculated that the electrical force between two charges also varies inversely as the square of their distance. Charles Coulomb experimentally confirmed this law of electrical force, which bears his name.
The analogy between Newton's Law of Universal Gravitation and Coulomb's Law of Electrical Force is a good one.
Like any analogy, it breaks down in places. Gravitational force only attracts, whereas electrical force can either attract or repel. The gravitational constant, G is a small number, whereas Coulomb's constant, k is large. The electrical force is a strong force, whereas the gravitational force is a weak force. The electrical force is due to a dearth or excess of electrons in an object, while the gravitational force is due to the mass of the objects.
Analogies can hinder as well as help learning. An analogy can lead the student to draw incorrect conclusions.
For example, students who believe that electricity in a wire is like water in a hose often conclude, wrongly, that if the wire is cut, the electricity will "leak out" (Glynn, 1998).
When stretched too far, analogies lead to misconceptions. For example, the analogy using water pipes, pumps, and valves breaks down with respect to the nature of electricity, which is a flow of electrons in a circuit, whereas water flows from one location to another due to gravitational potential energy or the mechanical force of a pump impeller. In electricity the electrons flow because of the voltage potential caused by their generation by either moving wires in a magnetic field, chemical reactions in electrochemical cells, or the discharge of capacitors.
The Teaching-With-Analogies (TWA) model (Glynn, 1995) provides guidelines for using analogies. Examining the analogies of exemplary teachers and textbook authors was instrumental in developing the TWA model. In this model the goal is to transfer ideas from a familiar concept (the analog) to an unfamiliar one (the target). If the analog and the target share some similar features, an analogy can be drawn between them. The process of comparing the features is called mapping.
The basis of the TWA model consists of six operations that the teacher carries out
when drawing an analogy:
1.Introduce target concept (the electrical circuit)
2.Review analog concept (water in pipes)
3.Identify relevant features of target and analog (the flow variables rate and pressure)
4.Map similarities (rate of flow is current, pressure is voltage)
5.Indicate where analogy breaks down (electrical generation and circuit)
6.Draw conclusions (resistance, current, voltage)
For students, an analogy functions as an initial concrete model of the target abstract concept. This model is useful because it draws on the students' existing knowledge. Later, when the students learn more about the target concept, they may adopt more sophisticated models of the concept.
Bruning, (p 353) states that four conditions are necessary for these conceptual
changes to occur:
(1) the student must be dissatisfied with current conceptions
(2) new beliefs must be intelligible and able to explain the concepts
(3) the explanation must be plausible, relating meaningfully to existing knowledge
(4) it must be fruitful, to facilitate further investigation
The second and third condition can be facilitated by the use of metaphors in teaching science. A successful teaching strategy would use these metaphors to help develop science concepts.
The advantages (Boo and Toh, 1997) of analogies are:
1. They are valuable tools in conceptual change learning.
2. They provide visualization and understanding of the abstract by pointing to similarities
in the real world.
3. They may incite pupil's interest and hence have a motivational effect.
4. They force the teacher to take into consideration pupil's prior knowledge and may reveal misconception in previously taught topics.
But care must be taken in using metaphors in class because of preconceptions that the students may have. As mentioned before, these preconceptions may be helpful or harmful, depending on how the metaphors are used and how the students actually relate the metaphor to previous knowledge.
Roschelle (Learning in Interactive Environments: Prior Knowledge and New Experience)
explains that prior knowledge has diverse and problematic effects on learning. Prior knowledge is related to both failure and success. In learning, refinement, restructuring, and conceptual change occurs incrementally and gradually.
Success begins with an educator's cultivation of the ability to identify the students' preconceptions, and to discover the seeds from which knowledge can grow.
Our purpose, as educators, is to create people who are life-long learners.
Anderson, Tom - Commentary on Cognition of Learning Mathematics & Science
Boo, H.K. & Toh, K.A. (1997). Use of Analogy in Teaching the Particulate Theory of Matter. Teaching & Learning, 17(2), 79-85.
Bruning, R. H., Schraw, G. J., & Ronning, R. R. - Cognitive Psychology and Instruction,
Chapters 13 & 14; 3rd Ed. (1999) Merrill, Englewood Clift, NJ
Constructing Knowledge in the Classroom.http://www.sedl.org/scimath/compass/v01n03/construct.html
Glynn, S. M., Yeany, R. H. & Britton, B. K. (Eds.), The psychology of learning science (pp. 219-240). Hillsdale, NJ: Erlbaum
Glynn, Shawn, Russell, Alan and Noah, David (1995) - Teaching Science Concepts to Children: The Role of Analogies; College of Education; University of Georgiahttp://www.coe.uga.edu/edpsych/faculty/glynn/twa.html
Glynn, S. M., & Takahashi, T. (1998). Learning from analogy-enhanced science text. Journal ofResearch in Science Teaching, 35, 1129-1149.
Roschelle, Jeremy - Learning in Interactive Environments: Prior Knowledge and New Experience (University of Massachusetts, Dartmouth)