Marzano lists summarization as one of the top nine effective teaching strategies. This idea is reinforced by Avon Maitland teacher inquiry groups, who have recognized that students' introductions and conclusions improve as students' summarization skills advance.
Teachers help students develop summarization skills by
Activating Background Knowledge
A person's background/experience influences what he notices and understands when reading. If a student is going to be successful at identifying the important points to be included in a summary, we must ensure the student has the background to do so, or teach to create that background. If, for example, you want students to summarize instructions about how to use a piece of equipment in the woodshop, you might have students watch a demonstration before you have them read about how the equipment works.
Teaching Text Structures
Students will have an easier time summarizing when they understand the structures of texts. Teach students how to identify chronological order, comparison and contrast, problem and solution and cause and effect structures in texts.
Priming Students' Brains
Without a purpose for reading, students may struggle to identify the important information in a text. The teacher can help students by giving them a purpose for reading. "Read this article and summarize the safety tips you need to know when operating a table saw" will get a different summary from students than "read this article and summarize how to use a table saw."
Summarizing Lessons at the Opening and Closing of Class
When we introduce a lesson by summarizing what students are going to do and learn, and then close the lesson again by revisiting the key learning expectations of that class, we model summarization for our students.
Giving Students Tools for Encountering Text
Reading a text more than once is important to identifying and understanding information. Students also need to know how to 'mark' a text with symbols or words that indicate, this part is important, I agree with this, etc. If they are using textbooks, give students sticky notes for marking a text.
Explore note making as a way to help develop summarization skills. Visit http://en.wikipedia.org/wiki/Cornell_Notes