For the sake of argument, let's assume all persons in question are mature -- what is the youngest age you think appropriate for that person to be given the responsibility to watch children for two hours?
I think it depends on the maturity of the child doing the babysitting. You may want to check and see if your state has any age requirements for it to be considered legal and not endangerment. Some states have really strict laws regarding this and some even require children to be supervised by an adult at all times. You can find out easily by call the non emergency line of the police station local to you or contacting your county Jobs and Family services department.
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