Benchmarks for Science Literacy: Chapter 15 THE RESEARCH BASE


Research related to Common Themes has focused on students' understanding of the notion of system, on the theoretical and tentative nature of models, and on the concept of conservation. Some research has found that student misconceptions about certain subjects can arise from their difficulty in recognizing natural phenomena as groups or systems of interacting objects.

    11A) SYSTEMS 

The Science Curriculum Improvement Study (SCIS) curriculum led children to approach observation and analysis of natural phenomena by thinking of them as systems of interacting objects (Karplus & Thier, 1969). Research done in connection with SCIS indicates elementary students may believe that a system of objects must be doing something (interacting) in order to be a system or that a system that loses a part of itself is still the same system (Garigliano, 1975; Hill & Redden, 1985). Studies of student thinking show that, at all ages, they tend to interpret phenomena by noting the qualities of separate objects rather than by seeing the interactions between the parts of a system (Driver et al., 1985). Force, for instance, is considered as a property of bodies (forcefulness) rather than as an interaction between bodies. Similarly, students tend to think that whether a substance burns or not is being solely decided by the substance itself, whereas from a scientist's perspective, the process of burning involves the interaction of the burning substance and oxygen.

When students explain changes, they tend to postulate a cause that produces a chain of effects one after another (Driver et al., 1985). In considering a container being heated, students think of the process in directional terms with a source applying heat to the receptor. From a scientific point of view, of course, the situation is symmetrical, with two systems interacting, one gaining energy and the other losing it (Driver et al., 1985). Concentrating on the inputs and outputs of a system often requires a different, time-independent view, which students may not take to be an explanation. Students often do not seem to appreciate that the idea of energy conservation may help explain phenomena. Studies reporting students' difficulties with energy conservation suggest students should have opportunities to describe systems both as sequences of changes over time and as energy inputs and outputs (a systems approach) (Brook & Driver, 1984).

Student explanations of material change seldom include certain kinds of causes that are central to a scientific understanding of the world (Brosnan, 1990); for instance, that parts interact to produce wholes that have properties the parts do not. For children, wholes are like their parts. Brosnan (1990) summarizes all this by presenting two stereotypical views of the nature of change--the common-sense view and the scientific view (pp. 208-209):

"Characteristics of a common-sense view of change: 

Properties belong to objects

The properties of an object are the same as those of the bits that make it up--not all of which may be visible at any one time. 

There are many kinds of stuff. 

Changes in macroscopic properties are the result of equivalent changes in the microscopic particles. 

If properties change it is because the bits that cause the property have moved away, come into view, changed from, grown or disappeared. New properties can be caused by the arrival of new bits. 

Characteristics of a scientific view of change: 

Properties belong to systems

The properties of an object are different in kind from those bits that make it up. 

There are fundamentally only a few kinds of stuff. 

Changes in macroscopic properties are the results of changes in arrangements of unchanging microscopic particles. 

If properties appear or disappear it is because the arrangement of an unchanging set of continuing particles has altered--at a fundamental level substance is always conserved."