Preschoolers benefit from spending most of their time exploring in the real world, not playing on a computer. However, by using the computer with one child or a few children at a time, you can talk to them while they are playing a game so they get other lessons at the same time. They can learn to take turns, to help each other when they are having problems in the game and to translate the game into the real world, such as by finding shapes or colors in the room or building with blocks.
Instead of letting your child play a computer game just for fun, choose educational games. Since she is likely just starting to use the computer, she won't even realize that other types of games are available. Small children have fun playing games that are related to what they are already learning, such as letters, numbers, shapes and colors.
Choose websites and games that are easy for preschool children, who likely aren't reading yet, to navigate and understand. Buttons can prompt voice cues so children will know what to do, or give visual clues, such as a stop sign to end the game or a green arrow to go to the next page. Children this young tend to get easily frustrated if a game is too advanced for them, so the right sites and games will help them enjoy learning on the computer.
After using the computer with your child, talk about what he played, what he learned and how he feels about the activity. By doing this, you can find out how your child interprets his computer activities and which parts he likes and dislikes. If a child is not enjoying himself on the computer, it could be something simple, such as difficulty moving the mouse around or being bored with games that are too easy.