Octavalia · Whole and half steps
Two neighboring notes: is there a whole step or a half step between them? See them on the staff or on the keyboard. You start with the natural notes; sharps and flats come in once you get those without hesitating, and finally, whether the half step is diatonic or chromatic.
Whole step or half step?
Answer with the buttons or with your computer keys: W whole step, H half step (and, once they come in, D diatonic and C chromatic). Play the keyboard to hear the notes.
This is where you'll see if you got it right and, if not, why.
A pair is secure when you get it right the last four times, answering in under 3 seconds. What you find hard comes up more often.
A whole step is two half steps: on the piano, there's another key between the two. In a half step the two keys are right next to each other. This is the basis of intervals and scales.