I recall once, for example, a Reading test asking fourth-graders about a passage they'd read about the human tongue and taste buds. One question asked the kids four distinct things (their favorite food, its flavor, where on the tongue that flavor was found, and how the taste buds work), with the original scoring rubric (established by classroom teachers) instructing the scorers to dole out one point for each of the four elements listed above. The teachers writing the rubric imagined straightforward answers like "my favorite food is popcorn, which is salty" (two points!) and "I like apples, a sweet taste found on the front of the tongue" (three points!), a scoring system that worked fine at least until theory turned into practice. Once it did -- once those intransigent schoolchildren started swamping us with all their unusual and unexpected answers -- then the scoring philosophy of those schoolteachers had to be laid to rest and the genius of the testing industry could be brought to bear.
The kids, you see, weren't just saying they liked to eat "apples" or that apples were "sweet." The kids were saying their favorite foods were "grass" and "water" and "Styrofoam," too, and even when they were identifying normal foods like "pizza" as a favorite they were then saying it was "salty," "sour," "bitter," and "sweet" (a.k.a. the entire spectrum of four flavors the human tongue can recognize). Furthermore, the students would often list a favorite food with what seemed an incorrect flavor ("my favorite food is ice cream, which is salty"), and then they would say they tasted that flavor on the tip of their tongue, which is not where one would taste "salty" (the side of the tongue) but is where one would taste ice cream, assuming it was sweet. The first couple hours of this scoring project, in other words, were pretty much total bedlam, massive disagreements within the group of employees I was training about whether "toothpaste" or "ice cubes" could be counted as favorite foods ("no" to the former and "yes" the latter), or "bitter" could be counted as the flavor of pizza (originally "no," at least until we considered toppings such as anchovies and artichokes, so then "yes").