1. Although instruments have much wider pitch ranges than the human voice, they are grouped in families according to the SATB ranges they produce. Because of their wider ranges, though, instruments can overlap. The orchestral string family is a good example--each instrument overlaps its higher neighbor. This makes it sometimes difficult to discern whether one is hearing a violin in its low range or a viola in its middle or high range. It also allows composers to develop some wonderful melodic lines connecting from one instrument to the next.
2. A good introduction to the instruments of the orchestra is Benjamin Britten’s “Variations on a Theme by Henry Purcell” better known as “The Young Person’s Guide to the Orchestra.” This eighteen-minute work is well worth spending some time experiencing in class. There are several good videos performances available as well as audio recordings. The CD-ROM for this textbook includes a performance with a listening guide.