Bass clef
The bass clef is the sign at the start of a staff whose two dots sit either side of the fourth line: on that line is written F, the F below middle C. That is why it is also called the F clef.
All other notes are counted from the F line. The lines, from the bottom, are G, B, D, F, A; the spaces are A, C, E, G. The C an octave below middle C sits in the second space, and middle C itself on the ledger line above the staff.
The bass clef is used for lower notes: in piano music it is usually the left hand, the lower staff of the grand staff. Cello, double bass and low voices are written in it too.
Reading down from middle C: B just above the top line, A on the top line, G in the top space, F on the clef’s line. Each note stands right above its key.
Where it is taught: the studio’s interactive textbook, chapter 4, “The left hand and the bass clef”.