The Unit Study Concept: What It Is, What It Isn't, Just what is a unit study? In the broadest sense a unit study is a method of studying one or more subjects all related to a unifying theme. In the unit study approach you look at any or all subjects in the light of a particular topic, theme, or historical/cultural period, perhaps. It can be as simple as a short term study -- several subjects based on a unifying theme -- or it can be an entire year's curriculum revolving about a single unifying theme like character traits.

As defined by Suite 101 at http://www.suite101.com/lesson.cfm/17333/630/2