I was taught a method long ago and have had good success with it. Take a large glass jug with a lid that has small holes drilled into it and put a good number of minnows in it. Lower it on a rope to the school of Crappie and they will try to attack these minnows. Within a short time they are either so angry or so hungry it's just fish on. This method works well on Crappie that won't bite.