Most of the items that can be added to a Lessons page can be made "required." That is, students must open (if the item is a resource) or complete (if the item is a forum posting, quiz, assignment, question, comment or student page). Further, the Lessons tool allows instructors to require students to complete one item in the list before allowing access to other items in the list.
If you titled your page something other than Lessons, select the title of the page as it appears in your Tool Menu.
Note: For graded items, such as assignments or quizzes, you may optionally specify a particular point value that must be earned on that item before the requirement is met.
Check Don't Release Item Until All Prerequisites are Completed option, then click Update Item.