I posted this thread in the Waterfowl section, but I thought it was a good one for the Huntin School forum section as well.
http://www.theohiooutdoors.com/showthread.php?6053-Duck-Calling-Basics&p=109497#post109497
http://www.theohiooutdoors.com/showthread.php?6053-Duck-Calling-Basics&p=109497#post109497