Participial adjectives are tricky! Students confuse those -ed and -ing adjectives like "bored" and "boring" all the time. I explain that they are not past and present tenses but adjectives that come from verbs. Often these verbs, like "interest" are rarely used as verbs. Who says "history interests me"? The direct object takes the passive form and the subject uses the active form. I am interested in history because history is interesting to me. What complicates these even further is learning which prepositions to use. My favorite list is from Betty Azar's "Understanding and Using English Grammar", aka "Betty Blue", the Bible of ESL.
I once worked with a great guy named Irwin in Chicago who told me he explained that the "ing" is for the thing. Get it? "Thing" has "ing" , and people, who receive the feelings, use the -ed forms. The movie is exciting and the audience was excited. Of course people can be described with the active form. Sonny Bono once said, "My first wife (Cher) was interesting and my second wife was interested."
I draw a box on the board and say it's a movie. I make arrows go to a stick figure and tell my students that if the movie is the -ing, it makes the person feel the -ed (overwhelming/overwhelmed, boring/bored, etc.) Yesterday, however, I thought about something new. As I was explaining this, I told them that the -ed is typically a person. Then I was corrected. A student asked, "But people say their relationships are complicated." It is a status on Facebook. You're married, single or "it's complicated." And situations are complicated...
Teaching participial adjectives is complicated.