Summarizing facilitates learning by providing opportunities for students to capture, organize, and reflect on important facts, concepts, ideas, and processes they will need to access at a later time. It usually is paired with note-taking.
Summarizing teaches students how to discern the most important ideas in a text, how to ignore irrelevant information, and how to integrate the central ideas in a meaningful way. This increases comprehension.
When you want students to demonstrate understanding of the important ideas and concepts from lectures, videos, and passages in a synthesized way.