I think your teacher is either "full of it" or "misinformed"
While it may be true that in English we usually enumerate parts of the body from the outside in, I'd suspect it has more to do with creating a physical starting point that is furthest from our eyes and looking for a way to create a list without forgetting something. I doubt this is limited to English, but is more of a "human" thing.
For random objects, I'd suspect people probably sort from easiest to recall to most difficult, or from most to least favorite, from biggest to smallest, by what sounds right or just randomly... or according to a set phrase, rhyme or song that's established culturally.
Lions and tigers and bears, oh my!
It's raining cats and dogs
strawberry rhubarb pie
They fight like cats and dogs
They're playing a game of cat and mouse
I'll have a ham and cheese sandwich
Would you like some cheese and crackers?
I'm having a wine and cheese party
I feel like a rum and coke
I'll take a Coke and Lime
In some of those examples, the more important element is stated first, but in many, the order has been established naturally, with less importance to order. Saying that, I'm sure there are certain patterns you could find based on how things sound together, or how many syllables there are... but the opposite is not wrong.
Best Answer
Using the preposition in vis-à-vis " the road" normally describes an action that takes place in such a way that the normal progress of the thoroughfare might be blocked, or which calls attention to the act in progress.
Take, for example, the Beatles song "Why don't we do it in the road?" Here it means doing something (i.e., fornicating) right out there in front of everybody in such a way that people will stop and take notice. The Beatles were a British band, so that should put paid to any notion that in means something different in BrE.
To simply walk in the road means to put oneself in some danger from traffic.
Normally, to describe the simple act of using the road for pedestrian traffic alongside vehicular traffic, the prepositions up, down, or along are commonly used. They don't carry the connotation of mortal danger, though that may exist as well.
To walk on the road describes the relationship of one's feet to the road surface.