4ths and 5ths Naming On Instrument 1 2 In the next group of lessons, you will see a Perfect 4th or 5th illuminated on your instrument and you must identify it. Please press the Exercise button below.January 3, 2013 1 2 In the next group of lessons, you will see a Perfect 4th or 5th illuminated on your instrument and you must identify it. Please press the Exercise button below.