Most of the items that can be added to a Lessons page can be designated as 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.
Go to Lessons.

Select Lessons in the Tool Menu to display the page.
Selet Edit for the item that will be required.
Hover and select the pencil icon to access Edit menu for content item.
Require item.
1. Under Prerequisites & Requirements, check the box to Require that the student use this assignment.
2. Then, select Update Item.
To conditionally release based on prerequisites:
Select Edit for the item to be restricted.
Hover over and select the pencil icon to access the Edit menu.
- Check the box Don't Release Item Until All Prerequisites are Completed.
- Then, select the button Update Item.
Specify completion of prerequisites.
Select the checkbox Don't Release Item Until All Prerequisites are Completed, then select Save.