Biology can sometimes be difficult, particularly when describing things that we cannot see or abstract concepts that we cannot fully comprehend the first time round. Some students have the notion that Biology is boring, and that the subject requires only memory work to get one through. Others find the subject irrelevant. Yet others find it extremely technical with bombastic terms littering every other sentence in a typical Biology text. Many students base such perceptions on how they were taught Biology in school.

To overcome these views, I have sought to make learning Biology the exact opposite of what many perceive it to be: simple, exciting, relevant and comprehensible. One of the many tools I have employed to achieve this aim is the use of analogies. According to Ruhl, “An analogy is a comparison of something unfamiliar with something familiar in order to explain a shared principle¹.” Like a bridge that spans the gap between what a teacher wants a student to learn and what the student already knows, an analogy builds on the framework of the learners’ existing knowledge so that they are not starting from scratch¹.

Teachers in primary school and even kindergarten often use actual models or play things to facilitate the learning process and introduce new concepts in ways that are understood by the children. Such supposedly simplified presentations of concepts help students to make connections with the new knowledge. Similarly, an analogy allows students to form an initial mental model of concepts to be learnt based firstly on what they are already familiar with and then transposing it to the new knowledge. Analogies work because human reasoning is said to be primarily based on sparse data and the identification and comparison of patterns instead of logical inference²: we look at a new experience and try to match it with similar experiences in the past. Analogies are thus something one can use to establish and organise links among experiences and make them available for retrieval in the creative problem-solving process².

Glynn, Russell and Noah³ describe a Teaching-With-Analogies (TWA) model (first proposed by Glynn, Duit and Thiele⁴) that shows how analogies can be used in the teaching process. In this model, the goal is to transfer ideas from a familiar concept (the analog) to an unfamiliar one (the target). If both the analog and target share some similar features, an analogy can be drawn between them. The process of comparing the features is called mapping³. When using analogies, one has to go through the following steps³:

• Introduce the target concept (e.g. the DNA molecule).
  
• Review the analog concept (e.g. a long, twisted ‘ladder’).
  
• Identify relevant features of target and analog (e.g. the two side handles of the ladder contain sugar and phosphate units; the ‘rungs’ are made of pairs of chemicals called bases).
  
• Map similarities (e.g. ‘side handles of the ladder’ and DNA backbone; ‘rungs’ and bases).
  
• Indicate where analogy breaks down (e.g. a ladder is rigid; a DNA molecule can open up and be replicated).
  
• Draw conclusions (e.g. about the structure and function of DNA or about mutations occurring at the bases).

Ruhl¹ describes how analogies can be used to communicate complex medical concepts to patients. A list of very imaginative medical analogies, which I have found very useful in my teaching, has been gathered and listed in http://www.altoonafp.org/special_analogies.htm⁵. Ruhl¹ also suggests that in order to construct and use analogies effectively, one must understand what works and what does not. Five rules are suggested (adapted below) for teaching students (instead of patients):

1. An analogy works best when the concept being taught is new. If the student already has some understanding of the topic, it may be better to build on the already available framework.
   
2. Use analogies only if the concept is hard to grasp. Analogies take time to set up and explain. If the concept is simple, a straightforward explanation may be quicker and will not open the student to possible misconceptions from misapplication of the analogy.
   
3. Make sure the student understands the analog. If the students do not even understand the analog, it would not help in the understanding of the target concept.
   
4. Explain the specific similarities. Simply stating the analogy does not focus the learners’ attention on how it is similar.
   
5. Be aware of misconceptions the analogy may leave. Ruhl¹ warns that one of the greatest hazards of teaching by analogy is that the student may transfer inappropriate knowledge from the analog to the target and leave with misconceptions. Analogies can hinder as well as help learning³. When stretched too far, analogies lead to misconceptions: “An analogy is like a car. If you take it too far, it breaks down¹.”

After the target concept is learnt, the student should be able to learn new things without always going back to the analogy. Once the analogy has helped the student to understand the skeleton of the concept, the learner can now add further insights directly to this outline and build his own knowledge base. Thus the learner is ‘weaned’ from use of the analogy¹!

References

1. Ruhl, T.S. ‘The Altoona List of Medical Analogies’. Altoona Family Physicians Residency of Altoona Hospital Center for Medicine http://www.altoonafp.org/analogies.htm (Last accessed: 28 June 2003).
   
2. Lakoff, G. & Johnson M. (1981). Metaphors We Live By. Chicago: University of Chicago Press.
   
3. Glynn, S.; Russell, A.; & Noah, D. (1997). Teaching Science Concepts to Children: The Role of Analogies. http://www.coe.uga.edu/edpsych/faculty/glynn/twa.html (Last accessed: 28 June 2003).
   
4. Glynn, S.; Duit, R.; & Thiele, R. (1995). ‘Teaching Science with Analogies: A Strategy for Constructing Knowledge’. In Glynn, S. & Duit, R. (Eds.), Learning Science in the Schools: Research Reforming Practice. Mahwah, NJ: Erlbaum, pp. 247–273. [As cited in Glynn, S.; Russell, A. & Noah, D. (1997).]
   
5. Ruhl, T.S. ‘Analogies Coming Out Our Ears!’. Altoona Family Physicians Residency of Altoona Hospital Center for Medicine http://www.altoonafp.org/special_analogies.htm (Last accessed: 28 June 2003).