Intervals

What you’ll learn

An interval is the distance between two notes. Count the letters from one to the other, counting both ends: C to E is C, D, E, three letters, so it’s a 3rd. C to G is a 5th. C up to the next C is eight letters: an octave.

The staff shows an interval at a glance. A line to the very next space is a 2nd; a line to the next line is a 3rd. Odd intervals (3rds, 5ths, 7ths) go line to line or space to space. Even ones go from a line to a space.

Two 3rds can sound different, though. C to E is four half steps: a major 3rd, bright. E to G is only three: a minor 3rd, darker. On the staff they look exactly the same, so count the keys to tell them apart. Major and minor 3rds are what chords are built from, in the next lesson.

Worked example

What interval is D up to A?

1. Count the letters, including both ends: D, E, F, G, A. That’s five, so it’s a 5th.
2. Check on the staff. D sits in the space below the staff and A in the second space: space to space, so an odd number. A 5th fits.

Now a 3rd: is E up to G major or minor? Count the half steps on the keyboard: E to F, F to F♯, F♯ to G. That’s three half steps, so it’s a minor 3rd. C up to E has four, so C to E is a major 3rd.

Common mistakes

• Not counting the first note. C to E is C, D, E: three letters, a 3rd, not a 2nd.
• Counting half steps for the number. The number (2nd, 3rd, 5th) comes from the letters. Half steps only tell you which kind: major or minor.
• Thinking 3rds that look alike sound alike. C to E and E to G look the same on the staff, but one is major and the other minor. Count the keys.
• Letting a sharp or flat change the number. C to E♭ is still a 3rd, because the letters are still C, D, E. The flat makes it a minor 3rd.

How the lesson works

Every interval plays one note, then the other, then both together. There are three tasks, each needing ten right answers:

1. Name the interval. Two notes on the staff: is it a 2nd, a 3rd, up to an octave? After each answer, numbered dots count the lines and spaces.
2. Build it. “Put a note a 7th above D”: tap the line or space where it goes.
3. Major or minor 3rd? A 3rd on the staff and on the keyboard. Count the half steps: four is major, three is minor.