How can I disable back and forward in browser?

[Trainer Eddie]

I'm writing a simulation that will load different screens depending on an action taken by a student. I need a piece of code to disable the browser back and forward commands to maintain the integrity of the process flow. I'm not concerned about them turning off Javascript or anything, so don't worrry about it being defeated. I just want to keep navigation inside the browser based on user input, i.e. buttons that are hyperlinked to the subsequent page.
Thanks all.

[Twey]

Check the Referer: HTTP header. If it's not satisfactory, redirect them back to the page.