Let's talk about playing arpeggios. If you're like most music theory students, you have heard the term and been intimidated by it. A lot of people think that arpeggio is Italian for "hard to play." While I don't know the exact translation, the real definition of an arpeggio is just a 'broken chord.'
Note: If you aren't familiar with basic triads , you may want to read that article first.
Some people will argue with me and say that an arpeggio is more like a scale than a chord because it is a linear set of notes and not a simultaneous "tone cluster." True, but who cares? It's still a broken up chord.
Like a scale, an arpeggio is linear: it's a set of notes that you play one at a time either in order or otherwise. Like a chord, it is made up of only certain notes from that set. So an arpeggio is a chord played like a scale.
Let's try one!
Let's say we have an A major chord. It is made up of A, C#, and E. Instead of playing them all at once like we would with a chord, we play them individually:
A C# E A C# E A C# E A C#...
Here is a list of all of the major chords and their arpeggios, just so you can see how they all work. I recommend playing all of these on your instrument right now!!
So now that we know what these are. But what do they do, and how can we use them? Most melodies don't just use the previous or next note in a scale. There are some exceptions, such as Mary Had a Little Lamb. In the key of C:
E D C D E E E... Each note is right next to another one on the C scale. (Try playing this on an instrument to see how it lays out on the scale)
When we go from one note in the scale to the next note above or below it, this is called a step (whole step or half step, doesn't matter). Most melodies will at some point skip notes in a scale to get to the next note, likeTwinkle, Twinkle, Little Star. In C again:
C C -> G G A A G ... This is called a leap.
A C major chord is made of C, E and G. Notice how in the above leap, we go from C to G. These are two of the notes in the arpeggio/chord. So if you are good at playing arpeggios, you don't have to worry about finding that G note, you'll already know exactly where it is.
Both of these are very elementary examples, but I use them because everyone knows them so the don't require much explanation.
Here is another example that most people are familiar with whether they know it or not: bugle calls. Watch this video and listen to the melody. Notice how it only uses the three notes of the arpeggio (bugles can only play those notes).
Playing arpeggios is common in melodies because the contain notes that naturally sound good with the song's chords (because they ARE chords.)
(NOTE: If you are looking to improvise on a melody, try using arpeggios. Take the current chord you're in, and use those notes to expand the melody.)
Practice, practice, practice. Learn lots of arpeggios on your instrument. Start by naming a chord: F. Use the notes of that chord: F A C, and play them all in order: F A C F A C F A ... going up through several octaves until you get familiar enough to play them in your sleep. This will make you a much better player and will make learning all songs much easier. Playing arpeggios is one of the FASTEST ways to get better on your instrument. It is also one of the fastest ways to start understanding general music theory and IMPROVISING!!
Hope this helps! Practice hard and let me know if you have any questions!