In some of the previous chapters you learned how to reduce extraneous cognitive processing (processing caused by poor instructional design) by eliminating extraneous words, pictures, and sounds (Chapter 8); by placing corresponding words and illustrations near each other on the screen (Chapter 5); and by refraining from adding redundant on-screen text to a narrated animation (Chapter 7). However, even if we greatly reduced or eliminated extraneous cognitive processing so learners could focus on learning the essential material, they still may be overwhelmed by the complexity of what they are trying to learn. In Chapter 2, we introduced the concept of essential cognitive processing that results from the complexity of the to-be-learned material, particularly when the material is unfamiliar to the learner. In this chapter we focus on situations in which learners must engage in so much essential processing that their cognitive systems are overwhelmed. In particular, in this chapter we focus on techniques for managing essential processing, including segmenting (breaking a lesson into manageable segments) and pretraining (providing pretraining in the names and characteristics of key concepts). This chapter represents an update on the growing research base on techniques for managing the learning of complex material.