Participial Adjectives confuse even the best English speakers, so it’s understandable that they are nearly incomprehensible for Japanese learners of English. As a teacher, I still have difficulty understanding the difference between the usage of “bored” and “boring”. A handy trick to remember is that adjectives ending with -ed often represent a feeling.
Additionally, when teaching the -ing forms it is best to avoid the verb meanings, as they confuse the student. A school that I once worked at had a teacher attempt to teach “boring” by using an auger on a piece of wood, which resulted in the student – a carpenter by trade – to associated “boring” with “exciting”.
When teaching the participal adjectives, teach them in pairs. The teacher performs an action that is represented by -ing, and the student explains their emotion in terms of the matching -ed form. For example, the teacher crawls under the desk while they have the student pretend to watch television. Maneuver your head between their legs and the table, and look up at them. The student should exclaim “I am surprised! This situation is surprising!”. Switch and repeat the exercise. For exciting/excited, have the student hold a balloon and dance while you clap. Avoid teaching pleasuring/pleasured.
Let the student know that not all adjectives follow this pattern. There are pairs such as scary/scared, comfortable/comforted, and delightful/delighted that should be learned separately.