The 3b Musical Reading use the same 3 notes C E F 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 F _ _ _ _ _ _
|E F E C||E C E F||C E F C|
|E C F E||F E C E||F F E E|
|C C E F||E C E F||E F E C|