'Probably the best book on teaching'; Teaching School, by Eric W. Johnson. Boston: NAIS, 4 Liberty Square. $8.95.

Mr. Johnson makes the following declaration: "Be ingenious, persuasive, and constant explaining the relevance of what you teach. And don't exaggerate." Before I read "don't exaggerate," I was going to say this was the best book on teaching I had ever read. Now I'll just say that I think it might probably be the best or nearly the best, book on teaching I have ever read.

What's more, I don't agree with all of teacher Johnson's suggestions. But what I do agree with is the fact that he's combined theory with suggested practice.

And I particularly like the fact that he says good teaching is based on four key qualities: order, interest, spirit, and discipline.

The opposite of order, Mr. Johnson explains, is chaos, hence order is all-important.

But order without interest is stifling; that is, without the interest of those whom the teacher would teach.

I leave his explanation of spirit for you to discover and savor -- combined with suggestions of ways to handle discipline, of suggestions for keeping order, and methods for inciting interest. Following Mr. Johnson would make a better teacher of even the best of us.

He says he has read some 200 books on teaching and found them all wanting. But he's given some nuggests from his reading, two of which I share with Monitor readers.

It seems that some elementary school pupils were asked which they would prefer if they misbehaved, a spanking or a friendly talk with the teacher. They voted overwhelmingly for the spanking.

And to close, a note about two ways to teach mathematics. One is to take real pains toward creating understanding. The other is the old British system of teaching until you're blue in the face.