Scheduling simply means the job or activity of planning the times at which particular tasks will be done or events will happen. Block scheduling or blocking is a type of academic scheduling used in schools in the American K-12 system, in which each pupil has fewer classes per day. It is more common in middle and high schools than in primary schools. Each class is scheduled for a longer period of time than normal (e.g. 90 minutes instead of 50). In one form of block scheduling, a single class will meet every day for a number of days, after which another class will take its place. In another form, daily classes rotate through a changing daily cycle. Blocks offer more concentrated experiences of subjects, with fewer, usually half as many if going through a schedule transfer, classes daily.