Well chosen metaphors provide a connection to that which the students already knows, and offers order to the chaos of the new language and unfamiliar concepts. Perceived order enhances learning.

Aristotle compared metaphors to puzzles, and as puzzles, metaphors engage us in solving how one thing is like another. It is this engagement in the process of resolution that makes the use of metaphors so valuable in conveying and understanding complex concepts.

When students develop their own metaphors for new concepts (providing they have a fairly good understanding of the concept), they further strengthen their understandings because they are (a) negotiating the appropriateness of the metaphor they are working with, and (b) arranging their understandings in personally meaningful ways.