Dear jal102, your daughters physical, mental and emotional maturity will determine if she is "ready" for scuba instruction and certification. There is a huge difference in those things among 11 year olds. She may well be ready. We have certified some 10 and 11 year olds in out local reservoir, which is NOT full of trash, but is cold (60-68 F depending on season). You also need to to step away and let the instructor do his or her job. Also, if available, see if there is a "kids only" class. We have great success with those. Finally, I commend to you my blog post "to the parents of junior open water divers, right here on scubaboard. It remains on the list of "most popular blogs." As for Jamaica, there are many good scuba operations- I suggest each reputable one will appropriately limit and young diver to safe depth and conditions, and will have a private DM happy to join you for a fee. Heck, I'll go if you pay my way!
DivemasterDennis
DivemasterDennis