There are so many, especially the ones I saw as a kid. Anything from Prof. Julius Sumner Miller had me enthralled. But from my teenage years comes the enduring and possibly my favourite example. Prof. Carl Sagan in
Cosmos explains the fourth spatial dimension. I should forget it, I can scarcely grasp the premises even now decades later.
And also from university days, that a lungfish has physically much more DNA than a human.