Hi Lee Ann, 
Thanks for your question! As a general approach to that topic, maybe you have already seen our post on responsible volunteering with turtles.  I think it clearly states the benefits as well as the risks of volunteering with turtles.
However, unfortunately, we are not in the position to recommend one specific project, neither in Bali or anywhere else in the world. But I would recommend you to join our facebook group and put up your question there, I am sure that everyone there will help you find such kind of project – if it exists. Our impression is that there are only a few reputable programs at all and frankly speaking I doubt that they would allow children to join their activities. But good luck to you!