i find that answer a little too convenient.
it is true that school standards change with time .. but i remember suggesting once to colleagues that the reality may be purely relative to our perspective. instead, what if we are simply getting more familiar with teaching the same topics?
But if you've never been to a place before, you need more than a description of a place; you need an exact definition, or a precise formula for finding it. The curse of knowledge is the reason why, when I had to search for a friend's tent in a field, their advice of "it's the blue one" seemed perfectly sensible to them and was completely useless for me, as I stood there staring blankly at hundreds of blue tents.~ from "why we are so bad with directions" @bbc
This same quirk is why teaching is so difficult to do well. Once you are familiar with a topic it is very hard to understand what someone who isn't familiar with it needs to know. The curse of knowledge isn't a surprising flaw in our mental machinery – really it is just a side effect of our basic alienation from each other. We all have different thoughts and beliefs, and we have no special access to each other's minds..