I don't think his premise is true. He says we were all taught photosynthesis in elementary and high schools and now all we know is a phrase that has no meaning for us. In fact, no one teaches the whole story of anything in biology before college, and not everyone takes college bio. Those of us that did knew the answer. It's a question of how far into biology you've studied...
The Ask question... wrong! thing strikes me as simply a device to make this point.