This book is written based on the fundamental principle that it is important for the speaker's thoughts to be conveyed well to the listener.
Especially in grammar classes, the underlying premise is that we must first acknowledge the other person and that what they say has its own perfect meaning and that each and every word is valuable.
No matter how much accuracy is emphasized in grammar classes, what is more important is appropriateness.

It is not a question of correct or incorrect grammar, but rather a question of differences, and therefore the value of appropriateness that allows for efficient language use must be recognized.
The ideal direction for grammar classes is not to simply provide grammar knowledge, but to pursue a communicative language life through thinking and exploring why certain linguistic expressions are used and, further, discussing why other linguistic expressions are unacceptable.

In general, inquiry classes are conducted through a series of inquiry processes such as raising a problem, setting a hypothesis, collecting data, analyzing the data, testing the hypothesis, and drawing a conclusion.
With this kind of inquiry class in mind, this book is organized in the following order: 'identifying inquiry problems, conducting inquiry (collecting, analyzing, classifying, etc. language data), and solving inquiry problems.'
This reflects the point that grammar classes should be conducted using a discussion-based, rather than an injection-based, inquiry-based method.
You may do this alone, but sometimes you will need to discuss and negotiate with two, three, or more people.