Adjectives in -ed and -ing: Feelings and Reasons

Adjectives in -ed describe a person’s feeling. Adjectives in -ing describe the thing or person that causes the feeling.

• I am bored. — I feel boredom
• The lesson is boring. — the lesson causes boredom
• She was excited about the trip.
• The trip was exciting.

Common pairs: interested / interesting, tired / tiring, surprised / surprising, frightened / frightening, confused / confusing.

Not: I am boring when you mean you feel bored — that means “I cause boredom”.