What is the purpose of Dewey decimal brainstorming?

Answer 1

The purpose of a Dewey Decimal Brainstorm is to come up with various ways to categorize and organize items (for example, by size, shape, colour, theme, subject, etc). By doing this, topics are generated by creating a library classification system.

This is an exercise typically done in a classroom setting to expose students to the Dewey Decimal Classification system, how this system is used to organize library collections, and to show how libraries collections are catalogued.