 Hi, and welcome to Linear Pitch Theory, Lesson 6. Now today's lesson moves on to a new concept, builds on a lot of the stuff that we've already done. Up till now, we've done whole steps and half steps. We've named all the notes on the piano keyboard and on the staff. We've done major scales. We've done minor scales. And we've done key signatures. And we've looked a lot at the relationships between all of those different things. Now today, we're going to begin studying intervals. Now, an interval is a distance between two different notes. And there are really two parts to classifying intervals. There is a general description in that classification. And that's a number, typically. A second, a third, a fourth, that type of number. And then there's also a more specific descriptor. In the case of intervals, we might say something is a perfect fourth or a major third. And that's actually the next lesson. Today, we're really going to focus on that numeric classification of intervals. So let's go ahead and get started. First of all, there are two different ways to determine that numeric classification. One is simply by the letter name of the notes that we're dealing with. So let's begin by putting down some letters. We'll just write a scale, F, G, and A. We're not even going to worry about whole steps and half steps here at this point. We're really just talking about letters. So we can take a look at these letters and we can figure out the intervals between the letters in this way. The distance or interval between A and B is a second. So two adjacent letters form a second. Distance between E and F would also be a second. We can take a look at the distance between A and C and that is a third. And you'll see this pattern very, very quickly. So from A to C is a third. Let's use another one. From F to A would also be a third. From there, we can begin to see how these formulate pretty quickly. From A to D would be the interval of a fourth. From A to E would be a fifth and so on. A to F is a sixth. A to G is a seventh. And from A to the next to A would be called an octave. So this begins to get us this idea of intervals taking care of. So we can do some examples of this. Let's just see if you can come up with this real quickly. So let's do something like this. See if you can tell me the interval from G to D. So to do that, we'd do a little bit of counting. We'd think, OK, G and then we have A, B, C between the G and the D. So this would be a second, third, fourth, fifth. So the interval from G to D is a fifth. So that's one way that we can determine intervals. However, there is another way to do this. And I'd like to show you that now. And we can do that by taking a look at the staff. The staff gives us some really nice visual and spatial cues on intervals. So let's take a look. If we have any note, we'll use the note names that we used to start today. We have a note A here and then a note B right here. That provides us the interval of a second. So the rule is that if we have a note on any line or space, the next line or space would then be a second. So from A to B is a second, from G to A is also a second. An interval of a third, we can see very quickly, is from any space to the next adjacent space or any line to the next adjacent line. Simple enough, these are thirds. A fourth goes one step farther in a space, past the next space to a line, or from a line past the next line to a space, these would be fourths. We'll jump down here to the base cleft to do fifths. Start again on A. This is an interval of a fifth. And this is an interval of a fifth. A sixth goes one farther. A, B, C, D, E, F, or from a line past two lines onto the next space. This would be an interval of a sixth, of course a seventh. I know you're seeing the pattern at this point. This would be an interval of a seventh. And finally, an octave from A to A or from G to G. Any note to the next instance of that note, an eighth or an octave. This is the way that one can determine intervals. The next theory lesson will deal with our more specific identification of these intervals. But for now, I want you to get comfortable with the general classification of intervals, both looking at them on the staff as well as looking at the letter names and coming up with the intervals.