This is getting repetitive at this point but she most likely doesn't know what masturbation is and is just doing it because it's something that feels good to her. For an eight year old, it's probably no different to her than scratching an itch on her arm.

It really isn't. Perhaps you should educate yourself about child development and common indicators of abuse. Aggressive or advanced sexual knowledge can be an indicator of abuse, but this would not qualify as either.

Actually I do know a lot about it since this happened to a family member of mine and I've taken a few child development classes :-) maybe you shouldn't talk down to people who you don't know the situation of.

While child abuse is real, and teachers (like me) and people (like me) who have multiple degrees in child development, and who work with children (like me) are regularly trained on signs of abuse, masturbation is definitely not one of those signs. Aggressive, constant masturbation (to the point where the child is injuring themselves or others) is definitely a red flag, but this (based on the scanty description provided) is most definitely not. Child welfare services are overburdened and poorly funded as it is. If you were to report every child who masturbated as a possible case of abuse, there would be no way they could investigate actual, legitimate, concerning cases and children who need help would not receive it. If you have taken any basic child development classes, then you have learned the simple fact that children function on the pleasure principle. They find something that feels good and they do it. Because their brains (and social skills) are still underdeveloped, they don't understand there is anything wrong with what they are doing. That is why, instead of judging, punishing, or assuming abuse, you talk to the child about "private, personal time" and teach them about their bodies.