This looks like a duplicate but it's not. Here is the 2013 question:
In farms or on farms? The OP only wanted to know which sentence was grammatically correct.
- They live the quiet life on farms
- They live the quiet life in farms
Instead I would like to know why we say “on a farm” and not “in a farm”
I was teaching English to a small group of Italian kids this morning, and we were playing "Guess which animal am I". While it was easy enough to get them to say
Do you live in a jungle?
Do you live in a house?
Do you live in the water?
Do you live in a tree?
Do you live in a garden?
For one kid the question
Do you live on a farm?
proved to be quite a battle, so I pretended to be deaf when he asked Do you live in a farm? until he got the phrase exactly right.
However, it would be neat if I could provide an easy explanation or mnemonic for these kids to remember, apart from me acting decrepit and deaf again next week. Any ideas?
Please, no comments on my being pedantic and fiscal, I know it's not the end of civilization as we know it, if a learner says I live in a farm but the preposition on is used in this case, and parents pay me to teach their kids!