This document discusses different types of manipulatives that can be used in educational settings, including real objects, models, and mock-ups. Real objects are actual items that students can directly interact with to learn about subjects they have little experience with. Models are 3D representations that provide learning experiences not possible with real objects. Mock-ups are simplified versions of complex items that clarify how they work. The document provides examples and advantages of using manipulatives, such as increasing student interest and promoting cooperation, as well as limitations like expense and storage issues. It also offers guidelines for when and how to incorporate manipulatives into classroom lessons.