The Development and Use of a Pedagogical History for a Key Chemical Idea: the Case of Ions in Solution

Abstract

A pedagogical history for a chemical idea combines a knowledge of the historical and philosophical background of that idea with what is known about the teaching and learning of that idea and is presented in a format and language that should make sense to a student. The development and use of such a pedagogical history for ions in solution is discussed in this paper. The emphasis is at the upper secondary or lower tertiary level and attempts to illustrate how chemical knowledge is constructed. An understanding of the nature of chemistry is a planned outcome of the exercise. 1 Presented at the Royal Australian Chemical Institute Chemical Education Conference in Hobart, Australia, February 2004. Introduction Much has been written about the historical approach to the teaching and learning of chemistry. Schwartz (1977) suggests at least eight important outcomes of an historical emphasis in chemical education: chemistry is not a monolith rising toward omniscience but a subject often full of ambiguity; validation of ideas occurs through experiment, logic, mathematics, and even aesthetics; history dispels the notion of a single universal scientific method but reveals a wide variety of often intensely personal approaches; human diversity of scientists; the role of the imagination in the practice of science; value-laden choices made by practising chemists; social consequences of chemistry; and a revelation of the nature of truth albeit small-t truth. These eight outcomes are components of what Leopold Klopfer (1969) previously called scientific literacy. While the goals of scientific literacy are admirable Stephen Brush (1974) cautions us with respect to some of the possible outcomes. For example, young students might find the ambiguity and complexity of the origin of chemical ideas rather daunting and thus the historical approach could in fact rebound on us. However, Brush concludes that if the chemical ideas are introduced sensitively the historical approach could have “a redeeming social significance”. That is, a more realistic picture of science demonstrated through its history may reduce the hostility to science bred through an image of the robot-like scientist lacking emotions and moral values. Henry Bent (1977) also speaks about the difficult but desirable features of the historical approach to the teaching of chemistry. He compares the historical approach to the textbook approach and views chemistry in history as “risky, insecure, inductive reasoning, from properties to principles. It uses facts aggressively to capture concepts”. On the other hand, chemistry in textbooks is “safe, dependable, deductive reasoning, from principles to properties. It uses facts passively to illustrate ideas”. Chemistry curricula as revealed in textbooks have been criticised for their emphasis on algorithmic problem solving rather than conceptual problem solving (Nakhleh 1993) and Lin (1998) has demonstrated that exposure to history of science cases in chemistry can enhance conceptual problem solving ability. Klopfer (1963) demonstrated that gains in the understanding of science and its processes followed a study of history of science cases by students in US high schools. In spite of these positive research results the use of history in the teaching of science and chemistry in particular has received only limited support. In 1989 the International History and Philosophy of Science and Science Teaching Group (IHPSST) was formed with only limited representation from chemists. In fact, the role of history and philosophy of science in the discipline of physics has received more attention than has its role in the discipline of chemistry. Bent (1977) argues that from a history of science point of view “chemistry is more complicated than physics. A match dropped is physics. A match struck is chemistry. Free fall is easier to describe mathematically than combustion”. The importance of showing our students how chemical ideas developed in modern society has, n