Grand staff
The grand staff is a pair of staves joined by a curly bracket called a brace: the upper staff with a treble clef, the lower with a bass clef. Piano music is written on it.
The upper staff is usually for the right hand, the lower for the left. Both are read together, top to bottom: notes written one above the other sound at the same time. The bar lines run through both staves.
Between the staves lies middle C. On the treble staff it is written on a ledger line below, on the bass staff on a ledger line above. It is the same note, a bridge between the two: upward from it you read in the treble clef, downward in the bass clef.
A typical page of piano music has the melody on the treble staff and the accompaniment, chords or a bass line, on the bass staff. Start by reading one hand at a time, then put them together.
Where it is taught: the studio’s interactive textbook, chapter 4, “The left hand and the bass clef” and chapter 10, “Accompaniment: melody right, chords left”.