The 3b Musical Reading use the same 3 notes C E G that the previous 3a Musical Reading but the E is now in black. When you can read the full 3b Musical Reading easily use the NEXT link to discover the 4a Musical Reading and its new color music note.
3b - _ _ C _ E _ G _ _ _ _ _ _ _ _ _ _
|E G E C||E C E G||C E G C|
|E C G E||G E C E||G G E E|
|C C E G||E C E G||E G E C|