IN is used for countries, towns, cities, continents, enclosed areas, bodies of water, lines and spaces.
- There are many fishes in the sea.
- A lot of good places can be found in the Philippines.
- She used to live in New York City.
- The children are playing in the park.
- He should wait in the line to get into the concert venue.
- The shoes are in the box.
- Her cat sleeps with her in the bedroom.
- That man does not want to keep his money in a wallet.
ON is used for surfaces, directions and names of street or small roads.
- Her cat is sleeping on the bed with her.
- The water spilled on the floor.
- He found many ants on the wall when he entered his room.
- There are many lights on the ceiling.
- The great detective lives on Baker street.
- What food on the menu do you like?
- Please read the story on page 28 of your book.
- On the left, you’ll see the famous painting of the National artist.
AT is used for specific and exact places or points.
- He is standing at the end of the line.
- She waited at the lobby of the hotel for her friend.
- Please wait for me at the entrance.
- She was already at the door before I was able to knock.
- Please write your name at the top of the paper.
- She is always sitting at the corner because of shyness.
- The lady always waits for the bus at the bus stop.
All you have to do is to practice using them by making your own examples and using them in conversations. Of course, there are always exceptions to the rule, especially for this topic. It’s your task to find them out. ^^ You’ll learn about them if you immerse yourself in the English language. Ganbatte!
Note: What I wrote here is not everything yet. They are just general rules in using in, at and on.