In eighteen studies on summarization with students from grades three to eight examined by the NRP, readers improvedthe quality of their summaries of text not only by identifying the main ideas but also by leaving out detail, including ideas related to the main idea, generalizing, and removing redundancy. Further, the instruction of summarization improves memory for what is read, both in terms of free recall and answering questions. They found that readers receiving summarization instruction either by rule-governed or intuitive-summarization techniques performed better than controls who were told to find main ideas but who had no explicit instruction. The summarization trained students significantly outperformed the control group in the quality of their summaries and on a standardized test (Cunningham, n.d.).