The many roles of “explanation” in science education: a case study

Abstract

In this paper the role of explanations is discussed in relation to possible consequences originating in the polysemy of the word explanation. The present study is a response to conceptual confusions that have arisen in the intersection between theory and practice, and between science education literature and communication in authentic science classroom settings. Science classroom communication is examined in terms of one teacher’s word use during eleven lessons about evolution. The study contributes empirical examples of how disciplinary norms of valid explanations are manifested in science classroom communication. A dialogical analysis shows how the teacher provides three conversational structures: asking for acts of explanation, providing opportunities to talk about what explanations are in this context and providing opportunities to talk about explanations constructed by students. These three structures facilitate the process of learning how to evaluate and justify explanations. Three potential meanings of the word “explanation” are pointed to: an everyday meaning, a pedagogical–professional meaning and a scientific meaning of the word. It is suggested that the co-existence of these three potential meanings has communicative consequences in science education.

Appendix

Transcript conventions

301	Numbering of the lines in each transcript to facilitate reference to specific utterances or actions in text
↑↓	Rising and falling shifts in intonation are indicated by up- and down-pointing arrows
=But look here	‘Equals’ signs mark the immediate ‘latching’ of successive talk
[]	Square brackets mark the start and end of overlapping speech aligned in transcript to mark the precise position of overlap
Underlining	Indicate emphasis
°I think so°	‘Degree’ signs enclose hearably quiter speech
(0.8)	Numbers in round brackets measure pauses in seconds (in this case, 8 tenth of a second)
(.)	A micropause
[(Looks at screen)]	Additional comments, used for denoting of gestures and moves
Because e::	Colons show degree of elongation of the prior sound

Overview of lesson sequence

Curricular unit: biological evolution
Lessons (50 min)	1	2	3	4	5	6
Addressed topics	Evolution as topic in science class, How do particular traits develop? Assignment about giraffes’ long necks	The development of life on earth presented by giving an historical account of the development of life on earth, from big-bang to today	Historical models of the evolution of life, categorisation task	Historical models of the evolution of life, categorisation task	Commenting on previous events. Cell structure and DNA.	Why do we have a variety of attributes and characteristics? Reproduction of DNA in cell cycle.
Activity structure	1.Introduction 2.‘Brainstorming’ 3. Instruction 4. Group assign 1	1. Summary 2. Lecture 3. Whole class discussion	Repeated half class: 1. Summary 2. Instruction 3. Assign 2	Repeated half class: 1. Summary 2. Instruction 3. Assign 2	1. Comment 2. Lecture 3. Small group discussion	1. Summary 2. Lecture 3. Small group discussion 4. Instruction
Tasks and questions	Evolution and genetics: what do you think about when you see those words? Assignment 1: Why do giraffes have such a long neck? We believe that the giraffes of today, stem from giraffes with much shorter necks compared to giraffes of today? How come explain!	What did the world look like millions of years ago? And what will it look like millions of years ahead? Three different explanations for the development of life on earth: Creationism, Lamarckism, Darwinism	The three different explanations as goals for students learning during sequence. Assignment 2: Try to classify the different explanations into the categories Creationism, Lamarckism Darwinism	The three different explanations as goals for students learning during sequence. Assignment 2: Try to classify the different explanations into the categories Creationism, Lamarckism Darwinism	What was the difficult part when trying to classify and sort the different explanations into the three categories?, Are mutations good or bad, what does it depend on whether good or bad?	Will you hand over your mutation to your own kids? Instruction: Assignment 3 what happens with the offspring of cat with no tail, body builder and white elk—will offspring inherit traits?

Curricular unit: biological evolution
Lessons (50 min)	7	8	9	10	11
Addressed topics	Follow up. The development of life on earth. Phylogenetic tree.	Conditions for development of first living cells. Miller’s experiment on creating life.	Practical activity including beans and beakers. Instruction in textbook.	Practical activity including beans and beakers. Instruction in textbook.	Individual and population. Traits, DNA and explaining variation. What is eugenics? What are resistant bacteria?
Activity structure	1. Summary 2. Assign 3 3. Lecture	1. Introduction 2. Lecture 3. Small group discussion 4. Lecture	Repeated half-class 1. Instruction 2. Task work 3. Summary	Repeated half-class 1. Instruction 2. Task work 3. Summary	1. Introduction 2. Lecture 3. Small group discussion
Tasks and questions	Assignment 3 what happens with the offspring of cat with no tail, body builder and white elk—will offspring inherit traits?	What happened between primeval soup and the appearance of the first living bacteria? What bacteria will survive and why these?	Describe the characters of one bean, mix with other beans in the beaker, try to use the explanation to find the proper bean	Describe the characters of one bean, mix with other beans in the beaker, try to use the explanation to find the proper bean	How come that the variation among a species is so big?