Chromebooks are a great, inexpensive and simple solution for kids. But you may have discovered that it's not as simple to set up tools that allow you to limit and manage your kid's internet access. Hidden in the Chromebook, however, is a setting to allow creating "Supervised Users" which will give you the ability to keep an eye on your kid's activity.
On your own Chromebook account, visit "chrome://flags" in the browser. Then scroll down to "Enable Supervised Users," and select "Enable." Now when you create a new user, you'll be able to make it a "Supervised User." Once the account is made, you can visit the account management tool online at chrome.com/manage. You'll be able to monitor your kid's web activity and block sites in real time all on the web.
For step-by-step instructions on how to set this up and use it, check out the guide at OMGChrome.com.