I would bet I am in the minority, but I just want them to get some running in. I have basic plans on how to get 100, 150, 200 miles in during the summer. 100 isn't hard at all, but it is a start. In May, some ask for 110, some 150, some 200. Some don't ask at all and just do their thing. I imagine almost every coach preaches that the best way to have fall success is the summer work. The kids are smart, they know the more they do the better they will be. They also have a pretty good idea of what the first week or two will be like and that those days will be much easier the more they do in the summer. This doesn't really answer your question, but if my runners asked me, I would say 18-25 for girls and 20-30 for boys depending on their schedule, summer heat, etc. We are not a high mileage program like others, so some may laugh at that response, but it is what I would suggest.