Actually for being completely wrong. While a lot of species of whales wouldn't be able to fit a human in their throats, some definitely have big enough throats to make it possible. Particularly if they chomped the person in half first.
Now whether a person could be swallowed whole and survive 3 days or not is a completely different question, but its not what the teacher was discussing.
no they dont, but some could theoretically. There's also a few sharks that can and do (although extremely rarely) eat people. People long ago didnt distinguish between fish/whale/shark so Jonah technically could have been eaten by a shark, or some crazy fish creature we've never seen before too.
Now whether a person could be swallowed whole and survive 3 days or not is a completely different question, but its not what the teacher was discussing.