Hello and welcome back. I'm Joseph Hoffman,
and today we're going to be learning about intervals.
An interval is simply a measurement of the distance between two notes.
Let's come to the piano to see how they work.

So, let's say we wanted to measure the distance between these two notes.
You know, we could take out our ruler and say they're about one inch apart,
but, in music, we're not so interested in inches or feet.
We're interested in the distance of the sound between those two notes.
Now, you already know that, in music, we would call this a step.
We could say this note is one step higher than this note,
and so that's one way we could measure it. And, you know, if we went here,
you could say, oh, this note is a skip above this note. So now, we're a skip apart,
but what if we wanted to go this far, or this far, or even this far?
How do we measure that in music? And that's where we need intervals.

So, with intervals, we measure like this: we say, first note, second note,
so we call that a second. That's the interval of a second,
which is just a more fancy term for a step. Now, from here to here,
we'd call it first, second, third. It's the interval of a third.
We always have to measure starting from the first note: one, two, three.
That's a third. Then, from here to here is a fourth.
One, two, three, four: the distance of four notes is a fourth.
From here to here is a fifth, and then it keeps going from there. We have a sixth,
a seventh, and then an eighth, and another word for an eighth is an octave.
"Oct" meaning eight, octave is the distance of eight notes, which, you'll notice,
brings you from C to the next C. An octave always brings you back
to the note you started on. For example, from D to D, that's also an octave.
We can count one, two, three, four, five, six, seven, eight notes.
Brings us back to where we started.

Now, intervals can go up or down. Like, if we're starting on this G, and I say:
can you find the note a third above G? Can you find that on your screen?
Point to the note a third above G. You should be pointing right here.
That's a third above G, but I could also say: where's the note a third below G?
Point to that. Well, we count here as one, two, three; a third below G is right here.
Remember, a third is just a fancy term for a skip.
You're going to skip either one note up, or one note down.

Okay, let's start on D this time. Can you point to the note a fourth above D?
If you're pointing right here, you're correct. That's the distance of four notes.
We always start with one on our first note: second note, third note, fourth note,
and we call that a fourth. Another way to think about a fourth
is that it skips over two notes. Can you find a fourth below D? Point to it.
If you're pointing right here you're correct. Here's a fourth down from D.
We've skipped over two notes in between to make a fourth. This time,
let's start on an E. Can you find a fifth above E? If you're pointing right here,
you're correct. Here's a fifth. Fifths skip over three notes, or,
another way to think of a fifth is that it's a double skip up.
Just like in our pentascales, when we do a chord: DO MI SO.
Can you find a fifth below E? If you're pointing here, you're correct.
Here's a fifth down from E.

Let's try a trickier one. Can you find a seventh above this G?
Remember to count the first note as one. We go: one, two, three, four, five, six,
seven. That's the seventh note. If this is the first note, here is the seventh note
right here. Okay, last one: can you find an octave below this D?
If you're pointing right here, you're correct.
An octave is always going to be the same note you started on,
either up an octave or down an octave. So, from D to D makes an octave.
One, two, three, four, five, six, seven, eight.
Always remember to count your first note as one, and count from there.

Now let's check out how to recognize intervals on the staff.
You know by now that if you see a note going from a line to the very next space,
or, going from a space to the very next line, a step above or below, that's a step.
And now, we know the interval term for that, which is called a second.
So this is up a second; this is also up a second. Now if, on the other hand,
we go from a line and skip the next space to a line–a line to a line–
or, go from a space, skip a line to the next space, we know that that's a third.
A quick way to recognize the difference between a third and a second
is that, with a third, it's going to match line to the nearest line,
space to the nearest space. But, with steps, it changes from a line to a space,
or space to a line. As you read music, use that little trick
to quickly recognize the difference between a second and a third.
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