Van Der Graaf Demonstrations - Induced Charge

It's demonstrations like this that really show the limits of Inductive-only learning in Science. Don't get me wrong, inductive teaching is a powerful tool under certain circumstances, but how the hell do you design an activity to inductively derive all the complexities of induced charge? Even if you can come up with one, it won't have as much impact or be as quick to do as the mixed-method demonstration discussed below.