I want to display the Menu button (to jump to individual pages), only after students complete the course (answer the knowledge check questions.) 
Then the Menu is displayed if the students reopen the course.   Thanks!

I think you'll want to use a global variable for this.  Basically create a variable called something like "allow_menu".  Then, when they complete the activity that you want, set that variable value to true.  If it's one of our quizzing templates, we provide some text objects off the edge of the screen that show when the quiz is passed or failed, and you can use that to trigger your action.  If you want the menu to be instantly available, you can also fire a global event (under the Page action tab).

See image01 attached.

Then on your Master Page with the menu button, you'll set up an action like this (you'll probably want to set your Menu button's Start Visible property to false):

See image02 attached.

Hope that helps!

Thank you Nav!!!
This worked perfectly, and your instructions are very easy to follow!