A、Because children could learn skills such as counting, reading from experience. B、Because children could learn something useful

In the earliest times children didn’t have to learn any more than how to cope with their physical environment. They had to learn to be careful around moving objects, to draw back when they got too close to something dangerous. They didn’t need a special school to learn these things other than time school of experience. Nor was the school necessary for them to learn how to survive because their parents taught them all they needed to know about how to hunt and till the soil.
    But as societies become mom complex, people depended more on others who were living far away. So it became important for children to learn to read and write. When money was created, they needed to learn to count and calculate. Children had to know these things in order to survive in this new expanded environ-merit Because such skills could not be learned simply through first-hand experience, schools became necessary. So the children could be taught what we now call the "Three R’ s" - reading, writing and arithmetic.