I purchased these for my 8 year old son and he absolutely loves them.  These sunglasses fit him perfectly and comfortably.  They aren't too big to where they constantly fall off his head and they aren't too tight to where they cause him any discomfort.  The added UV protection is great for his eyes during the days when we are outside a lot.  I am not too confident that these would work well for a 10 year old unless they had a smaller head.  Since these are a perfect fit for my son at his age now I almost think these would be too small when he was 10.  But for smaller children I would highly recommend these.