Yes, I know this is a beta. But, that being said, I don't think Apple is going to change this by the GM or release. When you go into Single App Mode, lock it on a app, and then push home or try to lock the device, a message pops up saying When you try to exit, it pops up with the passcode. But there is a loophole. If you hard reset the device (hold home and power together for 10 seconds, the device will restart) while in Guided Access mode, it hard resets and then you can do whatever with the device. I found out that within my first 2 minutes playing around with Guided Access. Yes, you can set a passcode for the device, but then when the device restarts from the hard reset, iit is useless and the teacher has to come over and enter it and get them to the right app and enable Guided Access again. The only solution I can think of is this: The only way to get out of Guided Access without the passcode is DFU mode. It is the only way we can have iDevices in schools. Disable the power button, even disable hard reset, and make the only way to get out of GA without the passcode DFU. It has to be able to be reset somehow if things go way wrong, so just disable the power and home buttons unless it detects DFU. Just my two cents if we want to use iDevices seriously in schools.