To some degree the concept of integrated science teaching is based on the parallel assumptions that the universe has an inherent unity and that science as an attempt to provide an understanding of the natural world has a unity of purpose, content and process that is far more significant than the differences in language or focus between individual sciences. Those who press for integrated science teaching usually make the further assumption that the teaching of any subject should in some way reflect the nature of the subject itself. If the natural sciences are becoming integrated in their intellectual structure and are already unified methodologically, then, according to this assumption, science teaching should emphasize this by itself being integrated.
There is considerable uncertainty concerning the meaning of such terms as: discipline, interdisciplinary and integrated. Integration requires re-combination of previously segregated parts to give unity or to make a whole. One procedure advocated in practice is to mix the parts and hope that the significance of each part will be appreciated by the students. Another procedure, deemed more satisfactory by its proponents, is to show the inter-relationships and interactions explicitly by using team teaching methods, such that each is able to cross-refer to other relevant fields where appropriate. Another approach is to select a topic that is an entity in itself ([eg] air pollution, human ecology) and teach any science relevant to that topic. Integration is applied here in a very different sense from its usage with reference to the synthesis of a course from a universe of segregated parts. Where synthesis is attempted, ways are sought to combine the parts into coherent units. In the topic method, the starting point is the coherent unit, which is then examined for its constituent subject areas, the relevant parts of which are taught as part of the unit.
For a course or programme to be considered truly integrated, it is necessary that the concepts of science be presented through a unified approach. A unified approach can be designed in a variety of ways, such as:< 1. The conceptual schemes approach: Structural unity may come from designing a course around broad conceptualizations, the so-called big ideas of science. Concepts are selected for such a course that naturally make connections with various sciences ([eg] conservation of energy, atomicity, dynamic equilibrium and change through time).
2. The inquiry approach: Problem solving activities can also be used as a unifying organizational scheme. In this approach, the science teacher raises, or guides students to raise, interesting questions about the natural world that challenges them to seek answers and that necessarily involve them in the substance of many sciences.
3. The relevance approach: This might be further sub-divided into the environmental science and applied science approaches. It is possible to structure an integrated science course around questions of the social relevance and utility of science. Issues such as whether or not to locate nuclear reactors in geologic fault zones, the propriety of organ transplants, controlling the population, and problems of nutrition and health, are examples of what will necessarily involve students in exploring ideas from various sciences, as well as from social ethics.
4. The process approach. It is also possible to design an integrated science course in which the focus is the process of science rather than the content of any discipline. ([eg] how to ask fruitful questions, develop working hypotheses, collect relevant data, analyse it and make sensible judgments, takes precedence, in such a course over the mastery of a prescribed body of scientific knowledge.).