I'm looking at buying I-Pads for two girls for Christmas. One's a sophomore in high school and the other is a freshman. They have wi-fi in their house and would be using them for homework and the other things girls that age use them for. Both girls are straight A students and will be attending college in 2-3 years. I plead ignorance on this subject and would like some ideas/suggestions on what version or model would be most beneficial for them at this stage.