Is there any way to make sure my kid won't become a cyberbully?
You can do everything right -- supervise, discuss online responsibility, introduce media that's age-appropriate -- and your kid still might be tempted to bully others online or in person. Bullying is related to kids' social and emotional lives in general -- the Internet is just a convenient way to act on negative impulses.
It's important to stay aware of kids' online activities and monitor where they play and how they interact with others online. Eight and 9-year-olds like to experiment, and they don't necessarily understand the consequences of their actions. Many young kids also don't realize the difference between joking and bullying -- so make sure to talk about how it feels to be the target of unwanted "humor." Teach them how to use the internet appropriately. Talk about empathy, compassion, and integrity.
Plenty of kids act responsibly, and many at this age feel a sense of duty to keep their favorite online environments safe. But a kid who bullies is typically in some kind of crisis, and he or she uses the Internet to act out. There are signs of crisis you can watch out for, such as being withdrawn, secretive, fixating on digital devices, and having a constantly buzzing cell phone, as well as dramatic changes in behavior. You can enlist your kid's friends' parents to keep an eye on your kid, too.