 Okay, to this point we've taken a look at the basic parts of the chord, the root, the third, the fifth, and the seventh. And now we want to look at some extensions of those chords, mostly known as the ninth, eleventh, and the thirteenth. So we're going to take a look at a D minor 7 chord first and see how to extend that like this. Okay, so we're going to take our D minor 7 chord that we just played, and basically hopefully you've noticed by now that all of our chords are just stacked thirds, the interval of third, D to F to A to C, those are all thirds that give us that chord. Now we're going to continue to stack thirds, so a third above C is E. So if we play the third, the fifth, the seventh, and now the E we're going to call the ninth because if this is the seventh, seventh, eight, seven, eight, nine, gives us the E. Now you might say, well, isn't that the second scale degree of the D scale? It is, but when we go an octave above, we usually call that the ninth. So we're going to have three, five, seven, and nine. Now you might say, well, that looks like an F major 7 chord. It does, but the bass player is still going to be playing the D, so it really gives us a D minor 9 chord, okay, and here's the nine. Now if we move the thirds up once more, the fifth, the seventh, the ninth, and G is now the eleventh, then we get an 11 chord for the D. Now again you might say, well that looks like an A minor 7 chord or a dominant 7 chord. It does look like that, but it really depends on that bass note. So in this case we're calling it a D 11, and then finally 7, 9, 11, and 13 looks like what? It looks like a C major 7 chord, but with a D in the bass, we're calling it a D minor 13 chord. So let's take a look at all those together. Here is the D chord, just with a 7, we move our thirds up. Now we have the 9, the D minor 9, here's the 11, and finally here's the 13. And we're going to experiment with using these, even when the chord progressions don't call for 9s or 11s or 13s, sometimes we'll use those anyway because it makes the chord progression more interesting, and it also makes it easier to play on the piano from a voicing standpoint where your hands are going. So we'll do some more with that moving forward, but I just wanted to introduce to you what extensions are, and later we'll talk about how we're going to use those.