Restricted Navigation and Free Navigation

Hi Bob and welcome to Heroes! 

You can set up restricted navigation as an option under the Player Templates -> Menu and that would allow the learner to move through the lesson and then they could only view the previous slide and the current slide. This article gives you a few different examples on how to further lock your navigation. Additionally, if you wanted to have the user be able to return to a course after viewing it, you can set each slide to "Resume saved state" which will tell the course that when they're looking at it again to not reset anything.  You'll also want to ensure that from the player template -> other section you have the "Resume on Restart" feature set to "prompt to resume" and the user will be able to pick up where they left off. 

Let us know if you need anything else!