So today I thought I had found some odd bug in my iPad. I had the login screen (as seen here) but the onscreen keyboard would not come up no matter what I did. I reboot the iPad thinking it was stuck. Same thing.
Then I realized that my keybard was in my bag and the only way to type in the password to unlock the screen was via the keyboard! And since the Apple Keyboard does not have an on / off switch, I could not just turn off the keyboard to get the onscreen keyboard.
... if you use a Bluetooth keyboard with your iPad, it might help if if has an on / off switch if you plan on separating the two on a regular basis. Otherwise, you will have to enter passwords via keyboard or you will have to remember to turn off bluetooth on the iPad when you stow the keybard in your bag.
... also learned that if you have the keyboard connected and want to see / use the onscreen keyboard, you just tap the "eject" key to show the onscreen keyboard.
Note... that does NOT work when you are typing at the unlock screen