I’ll add that this piece and the arguments Bryan Caplan make in “A Case Against Education” are not really mutually exclusive:
“So do we forget much of what we learn in school? This is a glass-half-empty-or-half-full type of question. I find it impressive that we remember any course content a couple of decades later, in the absence of putting it to use. And bear in mind, memory will be better to the extent that a student mastered the material in the first place and had reason to revisit it in the intervening years. And with systematic review over several years, the memory of that material will be nearly indestructible.
If memory for what we learn in school really isn’t all that faulty, as I’ve suggested, why do people think it is? There are two reasons. First, we underestimate what we know, and second, even when we recognize we know something, we may not realize we learned it in school.
We may misjudge our knowledge because we are quick to conclude that a failure of memory means the memory is gone, unrecoverable. A reason people overestimate forgetting is that they don’t consider the most powerful method of determining whether something is in memory: relearning. Here’s what I mean. Suppose you started studying French in grade 6, and by grade 12 your French was good enough to engage in routine conversation. After graduation, however, you did nothing to maintain your proficiency of the language. Now, 15 years later, you’re planning a trip to Paris. Let’s pretend you take a French test and find you’ve lost about 75 percent of the French you once knew. Is that 75 percent gone, simply erased from your memory? It appears gone—after all, you couldn’t remember it for the test. Well, suppose you started studying French again. If 75 percent of your knowledge is gone, then for you to become as proficient as you were at the end of high school, you would presumably have to study 75 percent of the seven years it took you the first time. But that doesn’t seem right. Your intuition indicates you would relearn French more quickly than you learned it the first time. Your intuition is right. This phenomenon is called “savings in relearning”. Even if you cannot recall or recognize something you once knew, that doesn’t mean the knowledge is utterly gone; the residue of that initial learning is evident through faster relearning.
One reason we think we forget most of what we learned in school is that we underestimate what we actually remember. Other times, we know we remember something, but we don’t recognize that we learned it in school. Knowing where and when you learned something is usually called context information, and context is handled by different memory processes than memory for the content. Thus, it’s quite possible to retain content without remembering the context. This problem is even more profound when we encounter the same information in multiple contexts. For example, if I ask you on which continent Egypt is located, you will quickly answer “Africa.” But if I ask you where and when you first learned that, you will probably have no idea. If you were a second-grader who had learned that fact the previous day, you could readily tell me “I read it”or“my teacher told me.”But as an adult, you’ve encountered that fact scores or hundreds of times in as many different contexts. The fact remains, but the contexts are lost.”