OFFICIAL CURRICULUM

The explicitly stated programme of learning (or "course of study") - which states the intended content as well as the mode, sequence and progression of its delivery and course activities.

HIDDEN CURRICULUM

Everything that is learnt during college activities that is not an explicit part of the official curriculum.  This will often be unrecognised but can have a profound effect on students' perceptions of themselves, their peers, other social groups and authority figures.  It may shape the learners' attitude towards learning or towards the subject matter.

OBSERVED CURRICULUM

What can be seen as actually taking place within the "classroom" - which may be different from the intended official curriculum.  Variance may be due to a host of factors (organisational, behavioural, resource-based, etc.) or dependent on the tutor (expertise, capability, etc.) or the learners (motivation, behaviour, ability, etc.)

EXPERIENCED CURRICULUM

The parts of the curriculum (both official and hidden) with which the student meaningfully connects.  It is this that has educational impact, insofar as it shapes learners lives.

Reference: Pollard, A. & Triggs, P. (1997) Reflective Teaching in Secondary Education. London: Continuum

See also:

What is a Curriculum?

Curriculum Models

Factors affecting curriculum design

Quality Assurance & the Curriculum

Designing Schemes of Work