Aren't definitions enough?

"While" — two actions/processes happen simultaneously
"As soon as" — Too events occur at the same moment of time
"Until" — One actions is terminated by an event (start of another action, for example)
"After" — One action lies (on the time axis) to the left of some point (if a moment indicated) or the starting point of another action.
...
I'd suggest illustrating English tenses and time relations by means of a simple graphical notation: just draw a time axis and show everything thereon: a section would be a period of time (occupied by an action), a point — a moment of time. That's all!

As a non-native speaker who never had trouble with this matter, I am just wondering: What kind(s) of problem do your students have??