This document discusses the concept of correlation in education. It defines correlation as the relationship between different subjects in the curriculum. Correlation can be direct or reciprocal. There are three types of correlation: within a subject, between subjects, and between subjects and life/environment. Correlation between science and other subjects can be incidental or systematic. Incidental correlation occurs naturally through broad subject treatment, while systematic correlation requires careful curriculum organization and teacher cooperation. Examples are provided to illustrate incidental correlation in physics, chemistry, and biology lessons.