Lots of fun stuff in the "more pizza" discussion. There was (possibly) some uproar over the concept that one 18" pizza is bigger than two 12" pizzas. I say "possibly" because we don't know what percentage of readers did not comprehend this. We only know that the Daily Mail found some stupid comments among the twitter replies. We don't know whether those represent 1% or 90% of readers. I also note that some of those "stupid" comments looked suspiciously tongue-in-cheek, and others raised the somewhat fair questions of "it depends on what you want." If you can't get your pizzeria to divide your pie into the number of choices you would like, then two 12s might indeed be a better choice, and if what you really like is crust, then two 12s would be clearly superior.
The person putting this out was trying to make a math point, using pizza as an illustration, so those objections would seem irritating and beside the point to math people. Yet he did actually use pizza as his example, so he has invited the vampire across the threshold on that one. He also missed a trick in that is just barely works for 17" pizzas as well, because 17 squared is 289, one more than 12 squared times 2: 144 * 2 = 288). Maybe no one makes 17" pizzas, so the issue never comes up.
I read the story at Powerline, who blames this on liberals. That is a partly unfair generalisation - I know plenty of liberals who can do math, and am told that theoretical math depts at colleges are largely liberal. However, I think it not entirely unfair. Practical math people, including engineers, are much more likely to be conservative, and the liberals I know at work are mostly innumerate. Sometimes jaw-droppingly so, even among those with graduate degrees.
But the deplorers have their own problems here. At the conservative sites carrying this story, there is a lot of moaning about how everyone knew pi-r-squared when they were in school, and liberals have ruined our educational system and created a handbasket shortage because of excess supply of passengers.
The students in your highschool did not all know this. No, no they didn't. That is a false memory on your part. First, there were the children who went to special schools, in our case Laconia State School was the biggie. They were only a few percent, but those children are regular classes now and create the impression that things are much worse. I note in passing that while many of these children had genetic or prenatal problems, some were those who had bicycle accidents while not wearing helmets and you never saw them again. In my high school in NH 1967-71 - remember that NH is one of those states that has the best testing scores in the country year after year - there was about a 25% dropout rate. It was a crossover period from the early 60's and 30% to the late 70's and 20% in NH. Either way, they never dealt with pi-r-squared.
Nor did the kids in vocational or business math, by and large. There were vocational, business, and college tracks at the time. (This was a better idea, which we have lost because of false aspirational goals.) The first category only got taught concepts like areas of circles to give them an idea of such things, and to perhaps identify those mechanical students who could be given further instruction. Similarly, the business students got such things in hopes that they would at least get the idea that numbers could prove things, and there were ways of using them that were helpful. Some of that group understood concepts like squares and areas just fine, but were happy to drop it and get on to accounting and budgets.
People commenting about educational topics in a historical context on the internet are simply not a representative group of society at large. They remember what they and their friends learned, forgetting that this was not everyone.