The best single site I saw on the web introduces the concepts, terms, gives practical illustrations, and offers ideas for classroom activities.
A few thoughts on stock…
A holder of stock owns part of a corporation, which exists in its own right as a legal entity. If the corporation is sued or goes bankrupt, the holder of stock can lose no more than his investment in stock.
Some stocks pay yearly dividends to stockholders if they earn profits.
While owning stock is a form of investment similar to lending one’s money out on interest, the attraction for many people is that the value of the stock itself can grow if the company does well or becomes popular. You might be able to sell your stock at a much higher price than you paid, because although the company might not be offering additional shares of stock, people eager to own shares will pay you much more than you paid initially. This creates the aspect of the “stock market” which enters the territory of speculation or gambling: you buy in hopes that the price of stocks will rise; then sell later at a profit.
Let me know if you have further specific questions or want additional ideas.