Some types of curriculum include the overt curriculum, the societal curriculum, the hidden curriculum and the null curriculum. Although there are many formal definitions of curriculum, educational theorist Leslie Owen Wilson defines the concept as "anything and everything that teaches a lesson, planned or otherwise."
The overt curriculum is the most common conception of the term. Also known as the explicit or written curriculum, this encompasses anything that is part of the process of formal schooling, from written lesson plans and activities to textbooks and films. The societal curriculum is taught outside of school, forming social knowledge of the world. Venues for the societal curriculum include families, peer groups, neighborhoods, jobs and media sources.
The hidden or covert curriculum is derived from the nature and organization of schools. It is what children learn from the administrative structure of schools and the attitudes of teachers and administrators. Examples of the hidden curriculum include the lessons students take from practices, such as standing in line, raising hands to be called on and following a rigid class schedule. The null curriculum is any subject matter that is not taught in school, which can give students the impression that these materials are less important. For example, in American schools, the culture and history of many non-Western people is often covered only slightly or sometimes not at all.