The core rule

FormUsed forExample
-ing adjective The thing or person that causes the feeling The lecture was boring. (the lecture caused boredom)
-ed adjective The person who experiences the feeling I was bored during the lecture. (I felt boredom)
Simple test: Ask yourself: is this the thing that creates the feeling (-ing) or the person who feels it (-ed)? "The scary film" (it creates fear). "The scared child" (the child feels fear).

Common pairs

-ing (causes the feeling)-ed (feels it)Examples
boringboreda boring job · a bored student
excitingexcitedan exciting match · an excited crowd
interestinginterestedan interesting topic · interested in science
confusingconfuseda confusing question · a confused tourist
tiringtireda tiring day · a tired parent
frighteningfrighteneda frightening noise · a frightened dog
surprisingsurpriseda surprising result · a surprised look
disappointingdisappointeda disappointing film · disappointed fans
embarrassingembarrassedan embarrassing mistake · an embarrassed smile
shockingshockedshocking news · a shocked expression
relaxingrelaxeda relaxing holiday · a relaxed atmosphere
annoyingannoyedan annoying sound · an annoyed customer

Exercises

Choose -ed or -ing.

1. The documentary was really ___. I learned a lot.

2. I was ___ when I heard the news. I didn't expect it at all.

3. She felt really ___ after the long journey.

4. It was an ___ situation — everyone laughed at me.

5. The children were ___ when their team scored the winning goal.