We make sense of our world and go about our daily lives by engaging in concept building. We acquire and develop concepts so that we can gain meaning about persons and events and in turn communicate these meaning to others. Some concepts are clearly of more importance than others. The key concepts

provide us with the power to explore a variety of situations and events and to make significant connections. Other concepts may be meaningful in more limited situations but play a part in connecting unrelated facts. Every field of study contains a number of key concepts and lesser concepts

which relate to substantive and methodological issues unique to that discipline/ field of study. Not unexpectedly, scholars differ over their respective lists of key concepts, but there is, nevertheless, considerable agreement (see, for example, Hayes, 2006). With regard to the curriculum field there is a moderate degree of agreement over key concepts.