Portrait of Wolfgang Amadeus Mozart. Via Wikimedia Commons (public domain).
Almost all instrumental music written between 1750 and 1900 uses the same scheme, and those who recognise it hear something different from those who do not. It is called sonata form, it sits in the first movement of nearly every symphony, quartet, sonata and concerto, and to find your bearings you do not need to study it: you need to know that it divides into three moments and that each has a recognisable acoustic signal.
First moment. The music presents two different materials. The first arrives at once, usually energetic, rhythmic, angular, and serves to plant the home key. Then comes a transitional passage in which the music seems to bustle about without saying anything new, and that is where the shift happens. After that stretch arrives the second material, almost always more songlike, more relaxed, in another key. You do not need to know which: you can hear that the colour has changed and the air is different. This first moment is called the exposition, and in classical music it was repeated note for note, which is the greatest gift made to the listener: you get two chances to memorise the two themes before the trouble starts.
Second moment. The trouble. The music takes the earlier materials and takes them apart: it uses a fragment, repeats it in different keys, layers it, interrupts it, carries it into distant regions. The acoustic signal of the development is instability: nothing stays still long enough, you never arrive at a close, and you have the physical sensation of being far from home. Whoever gets bored in this zone usually has not registered the themes beforehand, and so does not recognise the pieces being thrown at them.
Third moment, and it is the easiest of all to hear. At a certain point, after the maximum tension, the first theme returns in the home key, just as it was at the start. That return is built to be perceived by anyone: there is almost always a long preparation, a held note in the bass, an accumulation, and then the thing you knew comes back to its place. It is the moment when people in the hall relax without knowing why. From there on the piece retraces its earlier path, but with the second theme brought home too, and this is the real purpose of the form: two materials that at the start lived in two different places end up in the same place.
In short, sonata form is a story of departure and return with a conflict in the middle, and it is the same scheme as half the films you have seen. It is no coincidence. That structure works on human attention, and those who use it have known so for two hundred and fifty years.
How to train, in ten minutes. Take a first movement by Haydn or Mozart, which are the clearest because the joins can be heard, and do three things. Mark at what minute the second theme arrives, that is, where the character changes. Mark where it starts to spin its wheels, that is, the development. Mark where the opening returns. Three numbers on a sheet of paper. Do it twice, and you start to hear them without counting.
Then, when the scheme is automatic, the interesting part begins, which is watching who breaks it and how. Beethoven stretches the developments until they become the centre of gravity of the piece. Schubert enters the second theme with a change of colour that gives no warning. Brahms disguises the return so that you notice you have come back only afterwards. Those choices, without the scheme in your head, are invisible. With the scheme in your head, they are the reason that music is great.