Depends on a lot of factors - childs temprament, the length of time, the time of day and where you live. Only you can judge that, but I don't think what you are suggesting sounds unreasonable at all. I think that all these things need to happen in increments, just like when you allowed them to go out to play. i.e. toddler - in garden with supervision, Age 4/5 - in garden watched from inside, out of garden - supervised, 6/7/8 - out of garden - watched from window etc etc. that way we are able to assess and risk rate what we allow them to do. Times have changed and we no longer know or necessarily trust our neighbours and often live many miles from family so can't rely on them. However, I am the youngest of 7, I often went home on my own at lunchtime from the age of 9ish to an empty house that was unlocked all day and made my own lunch. If I was ill I stayed at home by myself and never ever had any holiday care - sometimes my older siblings would be around, sometimes not. There was a bit of an age gap between them and me so by that age they were mostly out working or had left home. I also clearly remember looking after my two year old nephew for a week during the school holidays while his Mum was in hospital having his baby sister and everyone else was working - I would be 14 at the time. This was 30 years ago, but the world has not really changed that much in terms of danger for kids. We have as a nation become much more protective of our kids, which isn't a bad thing, but we are in danger of having 15 year olds that can't cross the road by themselves which can't be healthy.