When my kids were about 5 I gave them a hella old Android with Cyanogenmod. It wasn't powerful enough to do anything dangerous and they learned a lot about how

When my kids were about 5 I gave them a hella old Android with Cyanogenmod. It wasn't powerful enough to do anything dangerous and they learned a lot about how to use software just from screwing around with it. It had a camera, microphone, and speaker which already is a pretty good start for having a good time. They discovered infinite repetition by making the phone shout "BUTT BUTT BUTT" in the middle of the night.