Prepositions again - IN, AT & ON

Hi people.

The very first posts seemed to look too much at prepositions so I felt it was necessary to take a different road for a while. Now it seems that there is still a great need to keep reviewing some specific concepts.

When I start a student's first class(es) I usually focus on the problems associated with these three main PREPOSITIONS - IN - AT - ON as positional forms.

Why, you might ask. Well, it seems that this is where I might be able to instil an understanding of English as being not another challenge, but as being another essential tool towards a better understanding of our global community and a way towards better communication.
This said, the most I can hope for is to plant the seeds that one day may germinate into a better feeling for the language as well as an appreciation of how a better knowledge of this language will probably result in a better understanding of their own language.

To this end, let's proceed.
When learning to speak Portuguese I often had difficulties getting used to the genders of objects, something we don't have in English. I realized after a long, long time that these Portuguese speakers had had these genders drilled into them right from an early age and what seemed so difficult to me, was as simple and natural as so many of our prepositions are to us.

How do we make this sense of prepositions as vivid to learners of the language as they appear to us?

I try to create a similar KEYWORD of association for each of these prepositions.

For IN I suggest - INSIDE - This one word places all objects INSIDE their related environment.
While a book might be ON the table, the same book IN the table suggests that the table has a special kind of compartment for the book to be placed INSIDE it, very much as we had as children with our school desks where the top lifted up so we could place the material we had INSIDE.

For ON I suggest - SURFACE - Again we have a very visual clue to ON especially when we think of the sea. A boat or ship should float ON the SURFACE of the sea. The book ON the table is also placed ON a SURFACE as are chairs and tables placed ON a floor.

For AT I suggest - EXACT - While I am focusing on positional uses of these prepositions, AT as a time preposition very accurately shows the exactness of its use when we specify the EXACT time of an event. I will meet you AT 12 o'clock means 12 o'clock exactly.
In much the same way we state an EXACT position when we use AT to describe the position.
I will meet you AT the shopping center (Where exactly, can be seen below). I will meet you AT the bar.

IN Sao Paulo, we have a very famous building called the Gazeta building. All I know about the Gazeta building, is that it is ON (SURFACE) Paulista avenue, a very famous street IN Sao Paulo. If I knew the EXACT number of the address of this building I could say that it is located AT XXX Paulista avenue.

For the individual describing their residential address, there is the simplest form - I live ON Residential street. More exactly, I live AT XXX Residential street. For businesses, it is exactly the same deal.

IN the above AT example, I mentioned meeting someone AT the Shopping center. We refer to places using the AT preposition to be as EXACT as possible IN our references. AT the library, AT the Airport, AT home, AT work etc. With the other prepositions IN & ON, we can drill that location down to something more specific. AT the shopping center, we are already providing an EXACT reference where we might agree to meet AT the North or South entrance. If we agree to meet IN the Shopping Center there is always going to be a need to state where exactly AT is. I will meet you AT Starbucks IN the Shopping Center. OR, I will meet you AT Starbucks ON the first floor of the shopping center.

Testing this - AT the Shopping Center is EXACT. AT Starbucks is EXACT. IN the Shopping Center is INSIDE. ON the first floor is a SURFACE.

We cannot meet ON the Shopping Center unless it has been designed for people to stand ON TOP of it. We cannot meet IN an Airport if we consider that an Airport consists of not only buildings but also Runways and other facilities. We can meet AT the Coffee shop IN the Airport Terminal.
We must be able to see the crazy, ridiculous aspect of using the wrong preposition in all situations. We must be able to sense what is IN - INSIDE, ON - SURFACE & AT - EXACT to begin to come to terms with this demon referred to as prepositions.

Understanding deadlines when using UP TO, BEFORE, BY & UNTIL

Christmas is just around the corner and there are deadlines to be met.

Your work and Santa´s presents have to be ready before the 25th of December, by the 24th of December to be exact. At midnight of the 25th, he should have finished his deliveries and you should be relaxing with your family having celebrated a pleasant day without stress.

That is if you managed to meet your deadlines.

In English, deadlines are often established using a variety of expressions which include BY, UNTIL, BEFORE and UP TO, among others. Brazilian Portuguese relies on the word até.

The words BEFORE and UP TO infer a deadline by stating the day or date.

The work must be ready BEFORE Friday infers that the deadline is Friday but that the work should be completed on Thursday ready for Friday.
I need the number of hours worked UP TO (and including) the last day of the month BEFORE Friday. Here we see that the deadline inferred in calculating the number of hours worked is related to the range of dates from the first day (not defined here) to the last day being the end of the month.  Friday establishes a deadline for delivery as in the previous sentence.

BY and UNTIL are used to stipulate a specific deadline.

The work must be completed BY Friday. (This form establishes a priority and date that cannot be passed.)

You have UNTIL Friday to complete the work. (This form also specifies a date that cannot be passed, but greatly alters the concept of priorities). It is assumed here that there is enough time before the deadline to be able to prioritize other tasks as long as the deadline is respected.

What is most important here is to recognize the difference in the structures used. They ARE NOT interchangeable.

Contrast the difference in meaning by using  BY or UNTIL  in the following example.
I will be in the office BY 15:00 (3pm). This infers that the person is outside the office and will return to the office some time before, but no later than 15:00 (3pm).
I will be in the office UNTIL 15:00 (3pm). This, on the other hand, infers that the person is in the office and will leave the office at 15:00 (3pm).

As mentioned earlier, Brazilian Portuguese relies on the word até. This word translates primarily to UNTIL while BY is understood to mean até as well. Because of there being only a single word in Portuguese to mean both BY and UNTIL, there is often a lot of confusion as to which of these two words they should use. Whereas in English we might clearly understand what is implied through the use of one or the other, Brazilians will not always, "get" this difference.

To make things worse, the word até is also very close to the English preposition AT. This results in a kind of double translation where AT is read as até then translated into BY which ends up being used in the following way - "I'll meet you BY 15:00 (3pm)" when in fact the phrase should be "I'll meet you AT 15:00 (3pm)" 

Once you understand these difficulties it is up to you to make sure you communicate exactly what you mean.
"The last day or The deadline for delivery is day XXXX or date XXXX" might be easier to understand than "The XXXX has to be delivered BY XXXX".

While this situation may not always seem to be critical, the right choice of words reduces the doubts and head scratching that comes about through the misuse of similar meaning terms. For the native English speaker this is also a chance to reflect on how you communicate with other non-native users of English.