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For the Grade as: drop-down, select the Assignment Type that was created previously (e.g. Password Protection 1).
Go to the ADVANCED tab.
Check Make this subsection available as a prerequisite to other content.
Click the Save button.
Set Prerequisite
Set the prerequisite for the assessment Subsection on which you would like to set a password lock.
Click the Configure button for the assessment Subsection.
Go to the ADVANCED tab.
Set the Prerequisite: drop-down to the name of the password entry Subsection (e.g. Password Protection).