When I introduce this grammar point to my lower level students, I over-simplify it a bit, but for basic learners it seems to work more often than not.
I tell them that an activity is Exciting, Tiring, Boring, etc. (ING)
I tell them that people feel Excited, Tired, Bored, etc. (ED)
Usually they get the idea. It helps, until their own grasp of language is clear enough to discern the difference between active and passive. They see the patterns, I ask them what is different, and usually they can explain the difference.
The parade was exciting
The climb to the top of the mounting was tiring.
The president �s speech was boring
I was excited when I watched the parade/
I was tired after I climbed the mountain
I was bored while I listened to the president �s speech.
Hope this helps.
