Many of the facts we know we pick up in passing without really trying. We learn new vocabulary, for example, by attempting to imitate someone who uses words we do not know. Although schools do attempt to get their students to memorize vocabulary words, and students can manage to memorize them for the test, there is scant evidence that it is easy to retain or even use words learned that way. Similarly we can force children to memorize state capitals (in alphabetical order, no less!), but did you ever doubt that the way you learn geography is by traveling? When you learn geography by traveling, you remember it better. No one taught me about the geography of New Jersey as a kid; I just went there all the time.
People learn astounding amounts just by making note of the world as it goes by. When we watch a movie, we pick up information about accents, topology, occupations, and other aspects of foreign lands. Everyone knows about singing gondoliers in Venice; chances are they learned it from movies or postcards, not necessarily from travel, and probably not from school. We pick up such things without effort or explicit instruction.
Reading teaches us things, but we also learn a great deal through experience. We learn physics by playing baseball or driving a car, without knowing that those activities have taught us something about physics. We may not be able to explain why F=MA, but we probably know that a batted ball can knock a person down, or that cars can skid on ice. We tend to assume that learning is bound up in the ability to articulate the theory behind these phenomena, but an important aspect of learning is simply being able to predict what will happen next, on the basis of experience.
Using Incidental Learning
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