Have you tried Kid Mode? It offers its own lockscreen that requires tracing or writing a letter to unlock the phone. While in Kid mode the child can play games, watch videos and more. You can also add your games (other apps) to what they are allowed to do and it grows with them. Register and it offers age appropriate things for them to do. We used it with our kids until they were old enough to start asking to download their own games. Meanwhile there are draw backs. When we upgraded we let the kids have the old phones. They could still do all of the stuff they liked, but Kid Mode only works with a network connection, i.e. WiFi or Carrier. On non activated phones this meant the kids could only play if we had WiFi. Also there is no dialer on the lock screen so no accidents and they can only get to Kid Mode, that is until they see you unlock it once or twice.