Anyone commenting on this (whether saying 'yes' or 'no'), please first read the article. What it considers 'calculus', none of us here would consider calculus. Because very few 5 year olds are capable of understanding even something as basic as a line plot (or '2d graph' or however you want to call it). They simple do not have the neural matter to comprehend fairly advanced (from an evolutionary point of view) abstractions like the relationship between a value on an x and a y axis.
And of course someone is going to say 'but I did it' or 'my children do it' - sure. My 6 year old has a very rudimentary understanding of the relationship between area and volume, and speed and velocity (although I'm not even sure how much of it is real understanding or just parrotting; I'm not a very good teacher, I've learned by now, not so much in how I explain things, but more in reading feedback from students). But it's not applicable to the population at large. I've tried explaining to larger groups and at that age, understanding why 'half past 6' is called that, is already quite a feat. Let alone understanding that there's two 'half past 6's' in a day, and why that is.
