 In Islamic law, a person cannot marry until they've reached the age of puberty, but they also have to be mentally and emotionally ready. David Wood doesn't tell his followers that even if the marriage was consummated at nine and 10 years old, such practices were indeed common. He's trying to belittle that, but that's the fact of the matter. She was still playing with dolls when she was taken to Muhammad's house to consummate the marriage. Why was she allowed to play with dolls? We're told she hadn't reached puberty. She hadn't reached the age of accountability. So if puberty is the age for marriage, then Allah and Muhammad stand condemned. Puberty often begins around 11 years old, although anywhere between eight and 14 is considered within the typical range. Factors such as family history, race, diet, environment, all determine when a first period might occur. He's trying to disqualify all that because he's bent on trying to demonize the Prophet and thereby demonize all Muslims who want to emulate the Prophet.