This is what I did for my kids

Both of my kids spend lots of time on FB. Before FB was out, they read a lot about IPO and asked me if they should buy the shares. I provided them some ideas on pros and cons of IPO including possible risk. They decided to buy 10 shares together(original they want to buy 10 shares each and later changing thier minds). So I "bought" them 10 shares in my account at $38/share and they keep track the price. They were very upset 2 weeks ago but thinking about buying more (to average down the cost; it seems "average down" is human natural even a 12 years old child is thinking about the idea) at $25. I showed them the chart and taught them about the risk of getting falling knife .....It's fun seeing them tracking the stock price and there is additional topic among mom and kids :>).