When the material is complex, you can’t make it simpler by leaving
out some of the elements or steps in the explanation—because that would
destroy the accuracy of the lesson. However, you can help the learner manage
the complexity by breaking the lesson into manageable segments—parts that
convey just one or two or three steps in the process or procedure or describe
just one or two or three major relations among the elements. We recommend
that you break a complex lesson into smaller parts, which are presented one
at a time. We call this recommendation the segmenting principle.