Porpoising was described, including what causes it, how to avoid it,
and what to do if it is encountered.

Describing porpoising is not "training" in my book, it's merely
"describing." ;-)

Discussion of flying techniques on the ground, which is not followed
by specific maneuvers in the air, is of extremely limited value. I
can't tell you how often a student can describe in flawless detail on
the ground how something is to occur, but his execution in the air
will be radically different.

However, you might describe porpoising as aggravated bouncing; if you
can recover from a bounce, you should never porpoise.