Next give everybody three pieces of material. Tell them to throw one piece of material into the air so that it is about level with their eyes and to catch it with their other hand. After they have mastered this far from difficult task, tell them to start off with one piece of material in each hand and to throw the one in their left hand in the air, followed by the one in their right hand. While both pieces of material are in the air they will need to catch the first piece with their right hand and then the second piece with their left hand. Demonstrate this or else it will make no sense to anyone.
Once people have mastered this starting with either hand, tell them to use three pieces of material starting with two pieces in the left hand and one in the right. Get them to start as they did before throwing the first piece from the left hand, the second piece from the right, catch the first in the right hand and then to throw the third piece from their left hand and catch the second piece with that. Once they have got the pattern worked out get them to continue on with this pattern for as long as possible. From this point on give balls to those who have the idea of the pattern.
Needless to say that the more juggling equipment (clubs, rings, diablos etc.) you can bring along and teach people to use the better. Clubs may be a good option to give to somebody who has already learnt to juggle balls. Another option for somebody who already knows how to juggle is to start them practicing a few tricks (under the leg and behind the back are obvious examples if you don't know any).