Selecting an online game for your child might not be easy. Age group is a large factor in game selection. There are numerous sites that offer free games. By typing "free online games for [toddlers, teens, preteen]" to your favorite search engine you will find many sites that offer free games. Make sure to replace the brackets  together with your child's age group. Most free game sites provide a wide selection. Most free game sites display ads to fund the hosting and game creation.
Games selection by age bracket:
Toddler: This age bracket will be looking for colorful games packed with sound and motion. For instance you could find a game having a fury creature. This is a great way to teach your child how to use a computer also to learn.
Preteen: Children within this age group will have different interests depending on age. Younger preteens, 8 or 9, are looking for light strategy with many different colors and motion. Think about sonic the hedgehog being a good example of a colorful strategy game. Math games are good for this age group. As your preteen gets older they will be looking for more action and more challenging strategy. You will discover your preteen playing less at games depending on cartoons and more games depending on movies. Racing games are great for this age group.
Teen: Teens are often the targeted audience for game developers. Your teen may look for role playing games offering high degrees of strategy or might be looking to play war games. You will find less teens playing racing games.