Thier is lots of diffrent ways for a child,teenger or adult to make some extra money on the internet. The best is to fill in surveys most of these work by check so even if you dont have paypal or a credit card you can still get money in the post by check. www.Surveylot.com has lots of survey websites were you sign up to 20 websites and recive survey through E-mail, you can make up to £10-£50 pound a week by signing up to ten survey websites which take you up to a mazimum of 30 mins each.
Your second option is to write an article for a website like www.bukisa.com you write an article and send it to your friends and you get money for it im not entirely sure how it works but thats the basics of it the articles have to be a minimum of 200 words and a mazimum of 1000 words.
Your third but not final option is to give your opinion kind of like the first one but you get paid a little less but still good, it is to do a kind of survey about what you like and what you dont like. you also get chances to test new prouducts on the market then give your opinion on them.