One of the basic principles of modern curriculum construction is the principle of integration. All the knowledge and experiences to be imparted to pupils should be presented as a whole, as a totality or total experience. Even at each stage the materials to be presented should be integrated. Traditional curriculum did not have any psychological consideration in its framing. Too much compartmentation of subjects make the curriculum boring and budensome to studies. Specially at the primary and secondary level the pupil can not understand and appreciate the logical order into which subjects are divided. Differentiated curriculum or subjects for specialization can only be justified in upper stages. Knowledges and experiences accumulated so far are very great and vast. For the convenience it becomes necessary to classify them and they are broadly classified under three or four heads – natural and biological sciences, cosial studies and humanities (cultures). Each again may be further sub-divided into more specified forms. But knowledge and experiences as whole is one system - a unity or oneness runnig through the world. At lower and secondary stages, compartmentation of subjects is unpsychological. The usual subjects should be combined into the core or integrated curriculum. The essential characteristic of the co-curriculum is that it is child-centered and here the method should be thorough problem solving and activities organized by the principle of correlation.
In the educational philosophy of the German thinker F. Herbart, we first get clear idea of correlation of studies. According to him, the soul is a unity and ‘appreciation is the assimilation of ideas involved in relationship of a new experience by means of ideas already acquired.’ Ziller, afterwards, in his theory of concentration put the principles of association and integration and in an another way. According to him one subject, specially history, should be made the central one which should possess natural points of correlation with other subjects or activities. With his methodological arrangements of ‘gifts and conditions’, Froebel founded a new type of educational institutions. In Dewey’s activity based curriculum- cooking, sewing and textile works constituted the activity curriculum. It has been pointed out by educationists that ‘integration will be possible if we have an activity curriculum , if the controversy between cultural and vocational training is reduced, if the emphasis on traditional subject examinations is withdrawn, if education of children is informed with coherence and continuity from subject to subject, from class to class, from school to school and from school to work’.
In these days of ours when there has been ‘a tremendous explosion of knowledge and reformulation of the basic concepts in the physical, biological and social sciences has brought into sharp relief the inadequacies of school program’ the framing of school curriculum on the basis of the principle of correlation and integration is very difficult. Indian Kothari Commission (’64-66?) puts emphasis on a more unified approach in framing the entire school curriculum ……. and undifferentiated schooling before some specialization begins and to be successful, the reforms require an orientation in teaching methods, evaluation and guidance’.