Great post by Daniel Willingham in Real Clear Education (April 22, 2014):
You often hear the phrase that small children are sponges, that they constantly learn. This sentiment is sometimes expressed in a way that makes it sound like the particulars don’t matter that much -- as long as there is a lot to be learned in the environment, the child will learn it. A new study shows that for one core type of learning, it’s more complicated. Kids don’t learn important information that’s right in front of them, unless an adult is actively teaching them.
The core type of learning is categorization. Understanding that objects can be categorized is essential for kids’ thinking. Kids constantly encounter novel objects. For example, each apple they see is an apple they’ve never encountered before. The child cannot experiment with each new object to figure out its properties. She must benefit from her prior experience with other apples, so that she can know, for example, that this object, since it’s an apple, must be edible.