We have seen earlier the steps required for securing your iPad with passcode. iPad 2 also has another feature called smart cover locking which would prompt user to enter the passcode when opening the smart cover. iPad users can enable smart cover locking via the option provided as part of General Settings.
Navigate to iPad home screen and tap the settings icon
Then turn on the iPad Cover Lock/ Unlock feature.
Now this setting would lock the iPad and would prompt passcode whenever the smart cover is opened.