に (existence)
Marks where something exists
You’ll be able to mark the location where someone or something exists in a sentence.

教室に先生がいます。
kyoushitsu ni sensei ga imasu.
What do you think this sentence means?
There is a teacher in the classroom.
Mark the place where something exists
With あります and います, use に after the place to show where the person, animal, or thing is located.
机の下に猫がいます。
tsukue no shita ni neko ga imasu.
There is a cat under the desk.
Place + に + thing + が + exists
Put に after the location, then mark what exists with が.
部屋にテレビがあります。
heya ni terebi ga arimasu.
There is a TV in the room.
学校に先生がいます。
gakkou ni sensei ga imasu.
There is a teacher at the school.
かばんの中に財布があります。
kaban no naka ni saifu ga arimasu.
There is a wallet in the bag.
に vs で
Both attach to places. に says something simply is there; で says something is being done there. The verb decides which one you need.
に, exists there
教室に先生がいます。
kyoushitsu ni sensei ga imasu.
There is a teacher in the classroom.
います describes existence, so the place takes に.
で, happens there
教室で勉強します。
kyoushitsu de benkyou shimasu.
I study in the classroom.
勉強します is an activity, so the place takes で.
冷蔵庫に牛乳があります。
reizouko ni gyuunyuu ga arimasu.
There is milk in the refrigerator.
玄関に靴があります。
genkan ni kutsu ga arimasu.
There are shoes in the entryway.
動物園にパンダがいます。
doubutsuen ni panda ga imasu.
There is a panda at the zoo.
13 more examples in the grammar path — free for a limited time.