Mark Joyner, age 8, of Houston, Texas, for his question:

Who invented money?

Money was not invented by just one person. The idea grew step by step. At last it led to the kind of money we use today. The first idea was very simple. It started ages ago, before people learned to read and write. Even then, they liked to swap things. Maybe a farmer had more corn than he needed, but no bacon for his family. It seemed sensible to trade his extra corn with somebody who had an extra pig.

People traded all kinds of things with each other. But often a person had a hard time finding somebody to make the trade he wanted. This problem led to the first idea of money. There were some items that everybody wanted    maybe shiny metals or animal skins to make clothes. If a person had a lot of these popular items he could trade them for any of the other things he wanted. In different parts of the world, people chose furs, pretty shells or something else that everybody wanted. Some collected gold nuggets and used them as money to buy what other things they needed. But we do not know who started using things as money.