My 3 year old plays out by herself. We are the end house in our cul-de-sac and from my hall and living room I can see the whole street. However she's only allowed to the end of the house next door but one to us. Where we drew a 'magic line' and is not allowed to cross it.
She's completely aware of the danger of strangers. KNows to never get into a car with anyone, even her friend's parents. She's not to go into anyone gardens or houses without telling me first and has an alarm on her watch that goes off every 10 minutes, at which she has to come check in with me. This is for her own use. To remind her that she constantly has to let me know where she is and gives her sense of freedom. She regularly goes into friend's gardens and houses to play. Just as we always have kids round at our. I can't remember the last time I just had Niamh for lunch, and if it's a sunny dayout they all set themselves up in our garden for a picnic.
It's a wonderful place for her to be in, she feels comfortable going and ringing a friend's bell and asking them to come out. I'm close to the other mums as we all got to know each other so we were comfortable with the kids being at each others house and it's turned Niamh into an incredibly confident. self assured child. Who is very worldly, is great at socializing, and has a great group of friends.
What Niamh doesn't know, is that when outside I sit on the stairs or sofa doing work so I can always see her, us parents have an agreement, if a child turns up at their house they call their mum. Whther the mum knows they're going or not. And the 4 houses she plays at I can see their back garden from one window or other.
She thinks she's completely independent though and that's the important thing.
This is an excellent example of slowly transitioning and building autonomy in a small child! Not to mention building a great community. Love it!