Correct usage of ‘on’, ‘at’ and ‘in’ from a foreigner’s point of view

If you want to explain to a foreigner how to learn when to use these words, you can say that  the go from more general to more specific (in: more general, at: more specific).

in: for objects inside other objects, or for location in a big context: year, country,

on: on top of other objects, or for location in middle-scale contexts: day, street

at: for location on a very small scale: moment (exact time), at specific address