You don't think whales teach other whales stuff? I've seen cats teach stuff to their young. Whales are a lot smarter than cats.

Also, I've seen an octopus learn from watching another octopus. Octopi are smart. I think it's fair to assume that whales are smarter than octopi.

Chimps and gorillas who are able to communicate using human sign language teach that language to other chimps and gorillas.