Intervals are distances

A third is a shape, not a fact

An interval is the distance between two notes, counted in semitones. The green band below is that distance made visible — an elastic that holds its length. Pick a size, then slide the whole band along the keyboard: the notes change, the names change, but the distance and the sound of the distance stay the same. That is the entire idea.

Tap any key to move the band’s lower end there. Slide it around and press “Hear it” in different places.

What to try

Pick the perfect fifth and slide it everywhere. C→G, D→A, F♯→C♯ — seven semitones every time, and every time it has that same open, stable ring. Your ear is recognising the distance, not the notes.

Compare neighbours. Play the major third, then shrink to the minor third in the same place. One semitone of distance is the whole difference between bright and shadowed — remember that when chords arrive.

Count the dots. Each dot on the band is one semitone of the journey. Interval names (third, fifth…) are just labels for distances you can now see and count.

Continue in the course

This explorer pairs with the Scales & patterns section of the Essentials path, where the ideas are built up step by step — or head back to all explorers.