Knew the Beatles' music theory

How is it that songs in a certain key play notes that are not in that key?

Yes, you think a little rigidly about the key. That is perfectly understandable. When you see a song try to look at its notes and figure out what key it is in so you can understand it. It almost seems like these incorrect grades are interfering with your calculation and making it more difficult to figure this out.

I would say more important than that key , You should understand the concept of the Tone center understand. The tone center is the tone that all other notes in a song tend or fall back to. That's just because, in most pieces of music, the author creates a series of notes and chords that tend to revert to a main note and a chord that is built up from the main note. For example, a song in the key of E has the tone center of E. However, the tone center does not tell you which notes are right or wrong or good or bad. It just names the tone (a single note) to which everything pulls back again and again.

Let's face the key not as a series of notes that are right or wrong, but as one Set of notes, usually expressed as a scale, from which the song is written . That means that most of the things I write to include in the song, most of the pitches and chords come from this place. But they don't really have to. When I use other notes it can be pretty obvious to the listener that those other notes are unique and do not fit the key. Since music has been based on the major scale for 500 years, the listener can simply assume that the pitches are based on the major scale.

Over time, the concept of key tended to revolve around a major scale in this way, and any use of a chord or melody that did not correspond to the major scale of the key center tended to be characterized by the relationship to that major- Scale described. For example, if a song made up of notes in the E major scale always changes the 7th note of the major scale to be flat (in the key of E, it means D # is lowered to D), it is known as b7 but you can see that this implies that D # is the "normal" 7. We tend to use this language to understand specific notes and chords, even when used consistently. Even if the song never uses the D # tone and only uses the D tone, we will tend to say that the song is in E and has a lot of b7 in it. I think you can maybe see why it is important to think about the tone center.

One thing that will help is learning the minor keys and the chords harmonized from them, as well as learning the different modes and the chords that can be found in those modes. I found that when I started to understand harmony in this way, I could see things quite differently because now everything that was out of key was like, "Oh, that's coming from the minor mode of the tone center “or“ Oh, this comes from the Mixolydian mode of the tone center. ”But this is going to take some practice and you may not be ready for it just yet.

In Day Tripper, the roots of all chords are in the key of E, and much of the melody, as far as I can remember, is in the key of E. However, many chords are made up of pitches outside the key of E.