Forms are not a catalogue of the techniques (vocabulary) of the system. It also contains a set of principles (grammar) of the system (such as to use a kick to set up a punch).forms are not a catalogue of the techniques of the system.
When you learn "This is a book", you should be able to construct sentences such as:
- This is a pen.
- This is not a book.
- That is a book.
- ...
The ability to remember "this is a book" may not be as important as the ability to "create" your own sentences by using the same grammar - subject, verb, article, object.