It's a very good question, Delia. I think the answer is the teacher is going to teach vocabulary systematically and make sure that the students don't just learn the meaning of words, but know how to use a word.
So in teaching anthropology, anthropological, I would have the students listen to the word and repeat it at least three times, anthropology, anthropology, anthropology. Use it in a sentence from their textbook. So they get to see the whole sentence as it occurs.
And then I would talk about it to teach them how I would use it, making up other sentences. And then I'd have them use it. And they'd use it not just alone. But they'd use it in a sentence with a partner. And I'd have to do this again and again and again.
Knowing that all language learners aren't great learners at language. But some students just need to have more practice using the language and practice using the language accurately, not incorrectly.