"Now, this is the first declension. You take the word's stem (which is self-evidently the same in both the nom. and gen. forms) and attach endings to it."
"By the way -- when you get to the third declension you will need to use the genitive stem, because it's different from the nominative stem.
"Hi, welcome back! Today we're going to talk about the second declension ... By the way ---" etc.
The third declension fell about halfway through the semester. What did they do? Wait for it ...
Over and over again, they took a few (randomly selected) letters off the end of the nominative stem and attached the third declension endings to it.
Readers, I introduced this new (but not unheard-of) concept so carefully. We looked at the endings and the new nouns separately. Then together. We discussed common patterns in third declension nouns. We drilled. We looked for third declension nouns in readings.
After we had reviewed about four times, it seemed clear that my students were going to have as much difficulty with it the seventh time as they did the first time.
I am told that this is a not uncommon reaction to the third declension, and I'm baffled. Would it be better to introduce this declension first? Is there a textbook that does that?

