Curriculum Integration is a concept where all the content being taught is taken from several subject areas to focus on one particular topic or overall theme. Instead of studying math or social studies separately, the thought is to teach about one topic from different points of view or subject matters. Teachers collaborate to develop lesson plans and now even some educational book publishers are creating their books to allow for schools to begin curriculum integration.
For example, a class may study about The Ocean. To incorporate the subjects of science, math, and history, the teachers of each subject need to develop a lesson plan which all centers on the same topic. During math class, the students can learn how to calculate the depth of the Ocean floor. In science, the students will learn what the ocean floor is made of and in the subject of history, the students can discuss the historians who sailed on the Ocean and made discoveries of new land.
Another example would be the Victorian era. The subjects which can be integrated are social studies, literature, and art. The social studies lessons would be focused on the time period and the culture back in the Victorian era. The literature classes will read famous author pieces from this time period and discuss how the writings could be considered historical fiction pieces. The students would be introduced to Victorian art and then asked to write an essay using the concepts they learned through the reading of literature as well as the history of the Victorian time period.
Curriculum Integration is not an abstract concept but has taken many years to get schools involved with this form of instruction.
http://www.ascd.org/portal/site/ascd/menuitem.fdd976cd7e54fccddeb3ffdb62108a0c/