### 4f Textbooks

A 4f Textbook is essentially a 4f Notebook with special content protection. It has a cover with title and author information, chapter pages, section pages, and standard pages. For easy navigation, it includes a table of contents and fast navigation tools. A 4f Textbook is essentially an e-book: it is stored on the users own computer and can be used without any subscription to online service. The user has access to the book as long as he or she desires. Internet connection gives added functionality for some interactive content elements, like access to web pages.

### Using 4f Textbook

A 4f Textbook is essentially an interactive notebook where the authored text is read-only and cannot be changed by the user. The pages can include all the familiar elements of the 4f Notebook, like videos, audio, quizzes, mathematics elements and web content. Readers can solve assignments in the textbook, and store their solutions in the book, as well as add annotations to the pages. 4f Textbooks are available in the Four Ferries web shop. Textbooks can be synchronized over multiple computers via the 4f Server.

### Annotations and Comments

The reader can add own annotations, like comment boxes and highlighting, to a 4f Textbook. These annotations are backed up to the server, whenever 4f Studio is online. The annotations are also synchronized over multiple computers using the same 4f Studio account.

### Textbooks for Self-studies

A 4f Textbook is much more powerful than an ordinary printed textbook or standard ebook, and is particularly useful for self-studies. The textbook comes with assignments that the reader can solve directly in the book. The computer can check the answers to quizzes immediately. Most page elements are interactive, and can contain arbitrary embedded web content, like web pages, simulators, videos, games, etc.

### Self-studies in Mathematics

4f Textbooks are particularly well suited for self-studies in mathematics. The eMath textbook series covers all standard high school mathematics. The textbooks in this series use structured derivations for presenting mathematical arguments, in theory, in examples and in assignments. A reader can solve the mathematical assignments directly in the textbook. The automatic checker can then be used on solutions that are written as structured derivations. The checker goes through the derivation step by step, and checks the correctness of each step. The checker marks all steps that it has not been able to prove, to warn the student to check this step once more. The checker is an additional service that is available in 4f Studio.