A great trick that doesn't cost much more than a box of matches and a short preparation.
I have
changed the demonstration slightly. I don't trigger the ignition with one hand, but hold one of the
matches in one hand between my thumb and forefinger and the other match in the other hand.
I
then explain that I charge the left one negatively through concentration and the other one mentally
positively.
I close my eyes briefly, concentrate and bring both matches together.
Then they
ignite. It is important that they are held together so that not only one burns, but both.