What is the name of a book you use to learn about subject in school?

There are many names for books used to learn about subjects in school, but the most common are:

* Textbook: This is the most general term and refers to any book used for teaching a specific subject.

* Coursebook: This term is often used for books that cover a specific course of study, and may include exercises and activities.

* Reference book: This refers to a book that provides information on a particular subject, but is not designed for systematic study. Examples include dictionaries, encyclopedias, and atlases.

* Reader: This term is sometimes used for books that contain readings on a specific subject, such as literature or history.

The specific name of the book will depend on the subject and the level of study. For example, a high school biology class might use a "Biology Textbook," while a university level course might use a "Principles of Biology" book.

Let me know if you'd like to learn more about different types of books used in schools!