This diagram represents three major aspects of curriculum as it shapes what students do or do not learn. The upper two quadrants represent the aspect of the Overt Curriculum. This aspect contains those things that we formally teach and that are either learned or not learned by the student. This aspect is often the sole focus of traditional curriculum discussion and development.
Things formally taught refer to that which we openly claim and intend to teach as seen in such things as plan books, courses of study, and textbooks. In addition, traditional curriculum does little to inquire as to whether the outcome of what is intended to be learned is actually what the students do learn. (See: Intended versus Actual Curriculum Outcomes)
The lower-right quadrant represents the aspect of curriculum that while learned, is not declared to be formally taught. This Hidden or Collateral Curriculum is extremely powerful and contains a large body of knowledge learned by students. Such things as social groupings, how to play the game of schooling, and ideology are learned through the hidden curriculum.
Every curriculum, whether empowering or traditional, has a hidden or collateral aspect to it. In the case of teaching for empowerment, we need to reflectively examine what students are learning in the hidden curriculum in terms of appropriateness and significance of what they are learning.
The hidden curriculum particularly serves to form student values, attitudes, and truth assumptions as it plays out across race, class, gender, ethnicity, disability, and life-style preferences. In the case of curriculum developed for empowerment, the collateral curriculum is designed to supplement student learning in positive ways. It should be noted that the term "collateral" is associated with awareness of the elements in this aspect while the term "hidden" is usually associated with a traditional curriculum attitude of unconsciousness toward this aspect.
The lower-left quadrant represents the aspect of the Null Curriculum. The null curriculum contains elements of knowledge that are conspicuous by their absence; they are neither taught nor learned. Historically, this aspect usually contained items of social taboos such as premarital sex, homosexuality, and the like. It also contains knowledge about ideology and what it is, its effects, and its purpose. As well, spirituality in terms of the human psyche is also within this aspect of curriculum.